I had installed ubuntu 7.10 on my intel 845gv chipset with 2.4 ghz at 767 mb of system ram.After selecting the option from bootloader,it displayes a message starting up and just a black screen appears.sometimes it gives error image not found.and if i give init4,then it goes to the login window.plz help me 2 do this directly after i select the option in bootloader.Thank you.

Sounds like the X server isn't working properly. After you think it has booted (though the black screen still sits there), try pressing CTRL+ALT+F1 and see if you can get a text login. For example boot it the usual way, wait for a minute and when it sounds like it has done the boot sequence, try it out. If you get a text login, log in with the username and password you created during setup (note: password is not displayed on screen with asterisks or anything, it stays blank even when you type - be careful). Then check what your Xorg's configuration looks like:
Especially the video/graphics card driver is what we're after. Does it say 'vesa' or 'intel' or what? If it doesn't say 'vesa', you can try to modify it and see if the generic vesa driver gets you a (low-resolution) graphical login, after which you can start looking for a better driver for your chipset. To modify it, press q to exit 'less', then
Scroll down to the display driver line, change the driver from whatever it is to "vesa", press CTRL+O, then CTRL+X (save and quit), then CTRL+ALT+F7 to get to the graphical tty (which is black if I'm right), then CTRL+ALT+BACKSPACE to restart X. If it didn't help, you can get back to your text login via CTRL+ALT+F1, and re-try.

It's a start anyway..