I'm using CS4 Production Premium, Premiere Pro version 220.127.116.11.
I was having a bit of difficulty with CS4--menus not working, missing codecs, crashes, etc. I uninstalled CS4, ran Clean Script for CS3 and CS4, updated my video driver, and then reinstalled. The problems I was previously experiencing seem to have been resolved (knock wood), but now I have another issue.
I am working on a video in PP using clips I've edited in AE. Before CS4 started crashing, this project worked like it was supposed to. Now, when I open up the project in PP, I get nothing but black in the program monitor. Everything is still there (clips in the timeline, assets, etc.), but they don't show up in the program monitor. When I move the play head/current time indicator over a particular asset in the timeline, it just shows black in the program monitor. However, when I then click in the program monitor, the current asset shows up like it's supposed to. When it gets to the next clip in the timeline, it's goes back to black. Now, I can click in the program monitor for this second clip and it will show up, but when I go back to the previous clip (the one I had previously clicked and gotten to show up), it is black again. When I double click the asset in the timeline, it shows up in the source monitor like it is supposed to. I thought that maybe I needed to render each clip in the timeline, so I moved the time indicator to a clip, clicked in the program monitor so it would show up, set the work area to just that clip, and selected "Render entire work area." After rendering, it played back all black! I tried unenabling and re-enabling the clips, but that didn't work. I tried clicking the little eye on the track in the timeline off and on, but that didn't work, either. I've deleted a clip in the timeline and replaced it with the same clip, and that didn't work.
I opened another project for which I did not use AE, and that project worked just fine.
When I open the clips up in AE, they work like they are supposed to.
This is a wild guess but you might try rolling back to your earlier video driver.
and make sure that the display icon (the eye icon on the left side of the Premiere Pro track timeline) is on.
Hope this helps,