Windows 7 hangs at grub's purple screen when dual booting

I have installed a new laptop (Lenovo Z510) for dual boot Ubuntu 12.04 and Windows 7 64 bit. After several trials it now works, but I have a strange effect.

I always enter the Grub purple screen fine. Ubuntu always works. When I want to boot Windows however windows boots fine (I hear the Windows start sound) but I only see a blank, purple Grub like screen. I can operate Windows though, pressing three times the tab key and then enter shuts the PC down successfully.

Sometime a trick works like that: I press just the power key and the PC hibernates. When I switch on the PC afterward and choose Win7 in Grub again everything is working fine, this time with working screen. However I had to find the trick does not always work - maybe whether it works or not is just random :-(

The workaround is quite dirty, what can I do to get rid of it?

Thanks for your help!

I had the exact same problem (I was able to listen to the windows login sound even when the only think I saw was the grub purple screen).

Luckily I found a workaround:

• move the file 30_os-prober to 06_os-prober (because I wanted the windows entries to be listed first)
• run sudo upgrade-grub

And now it works fine every time... I do not not understand why and I have not tried to isolate if update-grub is enough or not.

So this sort of worked for me. I moved the /etc/grub.d/30_os-prober file to /etc/grub.d/06_os-prober, then ran update-grub.

This puts windows on the top of the grub boot screen. Then I tried many different options to start, restart from windows and ubuntu and what I have noticed so far is if I let the boot via grub, proceed by it self with no manual intervention and let the default 10s pass, it will boot into windows with no issues.

However if I manually select the "Windows 7" option in the grub boot screen using my cursor and then hit enter, I get the dreaded purple screen in windows.