Comment 31 for bug 197209

Mike Phillips:

I suggest you make some changes in your /etc/default/acpi-support file.

gksudo gedit /etc/default/acpi-support

Change "SAVE_VBE_STATE=true" to "SAVE_VBE_STATE=false"
Change "POST_VIDEO=true" to "POST_VIDEO=false"

Reboot and you may have better luck.