10.8.1 causing external projector to go to sleep

I rencently updated to Mac OS X 10.8.1 on my mid-2010 15" MacBook Pro and I'm experiencing an issue with external projectors going to sleep after just a few minutes of use.

I've been able to reproduce the issue with multiple projectors, multiple VGA cables, multiple Mini Display Port->VGA adapters and multiple MacBook Pros (both running 10.8.1).

I didn't experience the problem at any time prior to the 10.8.1 update, including while I was running 10.8(.0) - this issue is new to me since I upgraded to 10.8.1.

Here's what happens:

1. I connect a projector to my MacBook Pro using a standard VGA cable and Mini Display Port->VGA adapter. I'm using the same cable and adapter that I've been using for over a year.
2. After 5-10 minutes of use, the projector turns off (or goes into standby mode). I've tried this with two different projectors and the behavior is the same for both. The Mac does not go sleep in any way, only the projector is affected.
3. It doesn't matter if I am mirroring or not mirroring my displays - it happens either way.

Any thoughts?

Thanks,

-mike