If I have a USB flash drive attached to the computer Grub goes crazy and looses the graphical interface and fails when selecting options (says drive not found). Remove the stick and the system boots up fine. This probem did not occur on Suse 10.3 and I performed a new install (deleted the 10.3 partitions) of SUse 11.
Firmware has remained the same between 10.3 and 11 so I don’t suspect that.
I’m running a Pentium4 32bit computer with IDE hard-drive and IDE CD-rom. In a probably related issue the openSUSE11 install disc wont boot from the second DVD drive bay only from the first (This may have always been the case though not sure).
Some pc’s will rearrange drives and partitions when plugging in usb bootable devices. This can shift your device name, resulting in what used to be /dev/sda becomes /dev/sdb (or similar)
One thing you could try is to check the /etc/fstab.
If it’s setup with partition names (e.g. /dev/sda1) change the notation to device-by-ID. I think there is an option in YaST to do this automatically but I don’t have it handy at the moment.
The same goes for your boot menu file /boot/grub/menu.1st
Make copies of the original files before editing so you can always revert!