When I type make xconfig in the kenel source folder, I get the following message:
make[1]: `scripts/fixdep' is up to date.
*
* Unable to find the QT installation. Please make sure that the
* QT development package is correctly installed and the QTDIR
* environment variable is set to the correct location.
*
make[1]: *** [scripts/kconfig/.tmp_qtcheck] Error 1
make: *** [xconfig] Error 2

What's the problem and how do I fix it?

Hi!

Just install qt development package or just try "menuconfig" instead.

QT is the toolkit/widget set with which KDE (among other things) is built. Widgets are things like buttons, scrollbars etc - ie. most of the graphics which make KDE look the way it does.

The error message means that QT is either missing or incorrectly configured. It's hard to tell you how to install what's missing without knowing which distribution you're using, but if all you want to do is make a custom kernel you're better off just using 'make menuconfig' instead of 'make xconfig' as chii-chan says. It's less attractive, but no more difficult to navigate through.

I tried that and I get:
make[1]: `scripts/fixdep' is up to date.
HOSTCC scripts/lxdialog/checklist.o
In file included from scripts/lxdialog/checklist.c:24:
scripts/lxdialog/dialog.h:29:20: curses.h: No such file or directory
In file included from scripts/lxdialog/checklist.c:24:
scripts/lxdialog/dialog.h:127: parse error before "use_colors"
scripts/lxdialog/dialog.h:127: warning: type defaults to `int' in declaration of `use_colors'
scripts/lxdialog/dialog.h:127: warning: data definition has no type or storage class
scripts/lxdialog/dialog.h:128: parse error before "use_shadow"
scripts/lxdialog/dialog.h:128: warning: type defaults to `int' in declaration of `use_shadow'
scripts/lxdialog/dialog.h:128: warning: data definition has no type or storage class
scripts/lxdialog/dialog.h:130: parse error before "attributes"
scripts/lxdialog/dialog.h:130: warning: type defaults to `int' in declaration of `attributes'
scripts/lxdialog/dialog.h:130: warning: data definition has no type or storage class
scripts/lxdialog/dialog.h:143: parse error before '*' token
scripts/lxdialog/dialog.h:143: warning: function declaration isn't a prototype
scripts/lxdialog/dialog.h:146: parse error before '*' token
scripts/lxdialog/dialog.h:146: warning: function declaration isn't a prototype
scripts/lxdialog/dialog.h:147: parse error before '*' token
scripts/lxdialog/dialog.h:148: parse error before '*' token
scripts/lxdialog/dialog.h:149: warning: function declaration isn't a prototype
scripts/lxdialog/dialog.h:150: parse error before '*' token
scripts/lxdialog/dialog.h:150: warning: function declaration isn't a prototype
scripts/lxdialog/checklist.c:32: parse error before '*' token
scripts/lxdialog/checklist.c:34: warning: function declaration isn't a prototype
scripts/lxdialog/checklist.c: In function `print_item':
scripts/lxdialog/checklist.c:38: warning: implicit declaration of function `wattrset'
scripts/lxdialog/checklist.c:38: `win' undeclared (first use in this function)
scripts/lxdialog/checklist.c:38: (Each undeclared identifier is reported only once
scripts/lxdialog/checklist.c:38: for each function it appears in.)
scripts/lxdialog/checklist.c:39: warning: implicit declaration of function `wmove'
scripts/lxdialog/checklist.c:39: `choice' undeclared (first use in this function)
scripts/lxdialog/checklist.c:41: warning: implicit declaration of function `waddch'
scripts/lxdialog/checklist.c:44: `selected' undeclared (first use in this function)
scripts/lxdialog/checklist.c:46: warning: implicit declaration of function `wprintw'
scripts/lxdialog/checklist.c:46: `status' undeclared (first use in this function)
scripts/lxdialog/checklist.c:51: warning: implicit declaration of function `mvwaddch'
scripts/lxdialog/checklist.c:51: `item' undeclared (first use in this function)
scripts/lxdialog/checklist.c:53: warning: implicit declaration of function `waddstr'
scripts/lxdialog/checklist.c:56: warning: implicit declaration of function `wrefresh'
scripts/lxdialog/checklist.c: At top level:
scripts/lxdialog/checklist.c:64: parse error before '*' token
scripts/lxdialog/checklist.c:66: warning: function declaration isn't a prototype
scripts/lxdialog/checklist.c: In function `print_arrows':
scripts/lxdialog/checklist.c:67: `win' undeclared (first use in this function)
scripts/lxdialog/checklist.c:67: `y' undeclared (first use in this function)
scripts/lxdialog/checklist.c:67: `x' undeclared (first use in this function)
scripts/lxdialog/checklist.c:69: `scroll' undeclared (first use in this function)
scripts/lxdialog/checklist.c:82: `height' undeclared (first use in this function)
scripts/lxdialog/checklist.c:85: `item_no' undeclared (first use in this function)
scripts/lxdialog/checklist.c:85: `choice' undeclared (first use in this function)
scripts/lxdialog/checklist.c: At top level:
scripts/lxdialog/checklist.c:103: parse error before '*' token
scripts/lxdialog/checklist.c:104: warning: function declaration isn't a prototype
scripts/lxdialog/checklist.c: In function `print_buttons':
scripts/lxdialog/checklist.c:105: `width' undeclared (first use in this function)
scripts/lxdialog/checklist.c:106: `height' undeclared (first use in this function)
scripts/lxdialog/checklist.c:108: `dialog' undeclared (first use in this function)
scripts/lxdialog/checklist.c:108: `selected' undeclared (first use in this function)
scripts/lxdialog/checklist.c: In function `dialog_checklist':
scripts/lxdialog/checklist.c:126: `WINDOW' undeclared (first use in this function)
scripts/lxdialog/checklist.c:126: `dialog' undeclared (first use in this function)
scripts/lxdialog/checklist.c:126: `list' undeclared (first use in this function)
scripts/lxdialog/checklist.c:126: warning: left-hand operand of comma expression has no effect
scripts/lxdialog/checklist.c:132: warning: implicit declaration of function `endwin'
scripts/lxdialog/checklist.c:133: warning: implicit declaration of function `fprintf'
scripts/lxdialog/checklist.c:133: `stderr' undeclared (first use in this function)
scripts/lxdialog/checklist.c:148: `COLS' undeclared (first use in this function)
scripts/lxdialog/checklist.c:149: `LINES' undeclared (first use in this function)
scripts/lxdialog/checklist.c:151: `stdscr' undeclared (first use in this function)
scripts/lxdialog/checklist.c:153: warning: implicit declaration of function `newwin'
scripts/lxdialog/checklist.c:154: warning: implicit declaration of function `keypad'
scripts/lxdialog/checklist.c:154: `TRUE' undeclared (first use in this function)
scripts/lxdialog/checklist.c:187: warning: implicit declaration of function `subwin'
scripts/lxdialog/checklist.c:219: warning: implicit declaration of function `wnoutrefresh'
scripts/lxdialog/checklist.c:221: warning: implicit declaration of function `doupdate'
scripts/lxdialog/checklist.c:224: warning: implicit declaration of function `wgetch'
scripts/lxdialog/checklist.c:231: `KEY_UP' undeclared (first use in this function)
scripts/lxdialog/checklist.c:231: `KEY_DOWN' undeclared (first use in this function)
scripts/lxdialog/checklist.c:241: `FALSE' undeclared (first use in this function)
scripts/lxdialog/checklist.c:242: warning: implicit declaration of function `scrollok'
scripts/lxdialog/checklist.c:243: warning: implicit declaration of function `wscrl'
scripts/lxdialog/checklist.c:270: called object is not a function
scripts/lxdialog/checklist.c:305: warning: implicit declaration of function `delwin'
scripts/lxdialog/checklist.c:309: `KEY_LEFT' undeclared (first use in this function)
scripts/lxdialog/checklist.c:310: `KEY_RIGHT' undeclared (first use in this function)
/usr/include/bits/string2.h: At top level:
scripts/lxdialog/dialog.h:130: warning: array `attributes' assumed to have one element
make[2]: *** [scripts/lxdialog/checklist.o] Error 1
make[1]: *** [menuconfig] Error 2
make: *** [menuconfig] Error 2

Why is this??

I am using Mandrake 9.1 and KDE 3.1.

libncurses installed?

ncurses did it for menuconfig THANKS! Why do you think xconfig doesn't work

the reason was mentioned by chii-chan and gkneller - u need the qt libs and dev packages installed just like u needed the ncurses libs for menuconfig,..