I edit using proxy clips* in Premiere, which works well on my old system (win2k), but not the new.  I was using divx clips without any problem, only to discover that it was a fluke.   When attempting to do so again all I got was a black screen in the monitor and timeline windows, which as it turns out is not without precedent.  For future reference, divx version 5.11 will work in premiere (5.01 at the moment)  For anyone else wanting to use temporally compressed codecs successfully in an editing program, remember to set a high interval for your I-frames.

*Lower resolution versions of the video clips, which get replaced with the full resolutions when the final video is exported.