Fisrt of all back your grub.conf up and make sure you always have some kind of bootable disk around (CD/Floppy) that works
I've been in sticky situations with disks that once worked but now have bad sectors. Try knoppix for that purpose.
After it's backed up, remove :
# added by NeTraverse - DO NOT REMOVE THIS LINE, it's used for uninstall
kernel /win4lin ro root=LABEL=/ hdd=ide-scsi apm=off
# end added by NeTraverse - DO NOT REMOVE THIS LINE, it's used for uninstall
Should be out of your gnome menu. Should preety much get rid of it. Never used Win4Lin, but I'd look into that uninstaller they speak about. Check their website.
Try wine if you want to run windows programs under linux: