Be sure that you've checked "share drivers with other programs". Also, sometimes 8.5 will hang on "busy" - as in busy drawing the waveforms. When that happens, I select the offending clip (or track) and then Bounce to Clip which forces a redraw of the screen. Once the waveform is drawn, all is usually well. No need to shut anything down. It also occurs, since you said these are old files, they might be gone from the Pic Cache so Sonar is having to recreate each one and that could choke the system if there are a bunch of tracks' worth, although, from your system specs, that doesn't appear be much of an issue. Just some thoughts.