I had an issue with ubuntu no longer booting up and giving me the error message

"cannot find GRLDR in all devices. Press CTRL+ALT+DELETE to restart"

I did some searching but still couldn't get it to work.

I am using Windows Vista with Ubuntu installed (not on a separate partition, but "within" windows)

I solved the problem by using Shadow Explorer (to access Vista's shadow copies, for windows 7, see note below)

I copied the most recent versions of 'wubildr' and 'wubildr.mbr' to my flash drive and rebooted (leaving the flash drive plugged in)

It booted up just fine, not sure why it works , my best guess is the 'wubildr' and 'wubildr.mbr' files were corrupted on my hard drive.

Not a permanent solution, but if it works, I am not going to complain.

Note: If you are using windows 7, simply right click on 'wubildr' and 'wubildr.mbr' (separately) and select properties. Under the 'Previous Versions' tab select a previous version and click 'open', then copy the files to a flash drive.