I've got Ubuntu 12.10 and Windows 7 installed on my laptop. I've never had any problems with anything related GRUB or the OSs (at least not something strange that I cannot fix).
Well, GRUB went crazy, 30% of the times I start my laptop, it stops to read from the keyboard. I mean, I hit Enter / Arrow / E but it does not react. I guess something like keyboard driver is not doing its job. It wait 10 seconds and load Ubuntu.(Yes it wait 10 sec like always and load Ubuntu the way it should). 70% of the time, however, it is working perfect. I really can't catch when. Why it stop working?
I tried refreshing the GRUB (reinstalling), but it didn't work. Still the same once it work, once it doesn't.
Sorry if you had problems understanding this. I'm no native english speaker.