We nolonger test Premiere Pro 2.0, so support is as is. However I doubt that error is related to any of our charges.

Version checker does get uninstalled with 4.2.1, not with 4.2.0.

Here's another good one for you. I have not seen that since AspectHD.

In P2K v4.2.1 Beta, when I play the timeline, the colors and brightness of the monitor window change dramatically.

No such problem with v 4.1.6

We haven't changed anything related to that, so you have either change the playback form YUV to RGB (or visa versa) or a graphics card driver update will be recalibrated.

YUV/RGB playback is controlled by the Project settings, correct?

I haven't changed anything.

Playing back same exact project. So i'm assuming the settings are still the same.

With P4K downgrade, no change in colors/brightness when I hit space bar.

Don't assume, go to the playback settings and try. We haven't changed anything with playback under CS3.