Hi Linda,
I know that one of the updates does this and I've been told that this is what happens.
My expereince of this is through Plexus which now works and switches Vista to Aero Basic so either Plexus is fixed or one of the Window's auto updates has changed something.
Because Aero Basic uses the CPU for the GUI, you should find that the system slows down, but to be honest our test machine has Vista and a Pentium M processor with 1GB and poodles along fine even when showcasing our IKIQ software. You can drop a CPU monitor onto the Vista sidebar as see what difference A/Basic makes. I would imagine that most people presenting from a laptop have probably got better spec machines than our old test one. Not sure if I mentioned in the last post, but apparently in the Nvidia graphics chips that cause Vista more problems (we have an ATI X700) but not been able to test this.
Turn A/Basic automatically off is probably a reasonable solution for DW and won't impact much for those running full screen anyway, but I hope that this is an option rather than a requirement as Vista will eventually stabilise. You could (in Vista Beta) turn aero on/off via the run command but this no longer appears possilbe

.
Mack