Using high resolution stills in Premiere

[jpeshek]

I get a nasty green screen in place of some of my stills if I use alot of high resolution images either alone as a slide show or mixed in with video and audio clips. Doesn't always happen to the same image either when I export the same sequence again. I don't seem to have this problem if there are only a few images, and none of the images exceed the 4000x4000 pixel limit; in fact none are more than 3500 in any direction. This only occurs when I'm using the stills heavily, and it doesn't seem to matter whether I export to DV or MPEG-2. I have worked around it by shrinking the work area bar and exporting in smaller clips to DV, then splicing into a new sequence, but by then the video has been exported twice. Is this caused by my hardware not keeping up? Anyone else having this problem?

Athlon XP 2600+
1.5GB DDR 400
120GB 7200RPM system drive
300GB 7200RPM video drive
no antivirus running during export
set priority to "high" in task manager