I would agree that this seems isolated to win7+nvidia
Here are some details of the problem that will hopefully be helpful:
This bug seems to start as soon as you install nvidia drivers.
(At least for me.)
The one time I recall this NOT happening was on a fresh install
before *any* graphics drivers. For the first few minutes of windows 7,
VE seemed to run perfectly, but as soon as drivers from the nvidia
website (win7 64) were installed, the blackouts returned.
Windows was reformatted and re-installed, but this time it ran
'windows update' and installed nvidia drivers on its own, and
the crashes/blackscreens returned.
When your machine starts to crash, you receive this error message:
"display driver stopped responding and has recovered"
Googling that phrase shows that in past versions of windows, this
error has been related to aero + nvidia cards. This makes sense when
you consider that GUI-related compatibility options are all that help.
Some posts suggest this only affects people with more than 2
GB ram. (4 GB here.) A few of the posts even go into technical
details that might shed light on the hardware/software issues
of this.
Those are all the things that I noticed. Hope they help!