I've finally got it working. Here's what i did and what results i got. I Completely removed my virtual instruments and reinstalled them, Result: didnt work. I removed pt 7.31 cs5 and reinstalled it, re-patched it. No result. Finally I removed pro tools 7.31 cs5 and all it's drivers, then installed an older version, 7,1. Result: Great success! The midi timing is now accurate, the volume meters is not lagging and the timeline marker seem to move smootly. The resolution for faulty midi timing / virtual instrument screw-up / lagging timeline and volume meters on a core 2 duo win xp computer : Get pro tools 7.1. It seem to be the most stable release. Gives me the willies.