I have upgraded my FC6 installation to FC7 without any errors. At boot, FC6 attempts to start, and I get messages:

kernel /boot/vmlinuz-2.6.20-1.2962.fc6 ro root=/dev/sda1 rhgb quiet
Error 15: File not found
Press any key to continue...

Then, options to boot Fedora (FC6) or Fedora-base (FC7) are displayed. On choosing FC7, startup occurs with various warning and error messages related to missing files are displayed. After login, I see the new desktop background, but menu bars at top and bottom of the screen are blank.

Any ideas how to fix this?

Perhaps your grub.conf file did not get reconfigured properly,
Have a look at it (/boot/grub/grub.conf or somewhere similar) and make
sure it makes sense i.e. all the files referenced exist and the root= device
file ( /dev/sda1 in your post) is your / filesystem.

Otherwise post it up and I may be able to help.

Cheers
mike

What kind of HDD do you have? If it is an IDE drive, try booting the old kernel. Push e to edit it on the grub menu, select the line that starts with "kenerl", push e, and replace the /dev/sda1 with /dev/hda1.

YOur kernel must have been also upgraded........
rename the /kernel line in /boot/grub/grub.conf

If your system has an executable called grub-update (possibly in /sbin), execute it as root - it should check /boot for you and add any kernels found there. Not sure if it includes Windows boot sections if any. If that doesn't work (can't find the file for example), manually edit menu.lst and make sure there are only kernels that really exist in /boot, and that they are all in there.

After this you should probably run the dist-upgrade with yum again, to double-check that every package got correctly upgraded. This is the downside of upgrading trough package manager and not using the clean method of formatting + reinstalling.

EDIT: it's also possible that your settings are wrecked. You can test this by renaming any .kde or .gnome (.gnome2) directories under your home directory to some other name, for example
.kde -> .kde-backup
.gnome -> .gnome-backup
.gnome2 -> .gnome2-backup
and then logging out and in again. KDE/Gnome related settings should have been "reset". If it helped, remove the *-backup directories, if it didn't help, move them back to their original names.

Thanks everyone for your suggestions. Eventually, I just did an install of F7, rather than an upgrade. This worked without any problems, and I'm now configuring my F7 box as per my previous FC6 config. No problems so-far with additional apps, drivers, etc.

All a bit disappointing that this post-install configuration has to be done over again. Upgrading from FC5 to FC6 earlier this year proceeded without any of these difficulties.

Once again, thanks all.