PT 8 randomly ignoring or creating automation commands

[peemarl]

During playback, tracks are being muted where there is no mute or volume automation drawn. Drawn volume info in the edit window is sometimes totally ignored. The effect is that tracks should be playing but are not audible, but this doesn't happen every time.
I can start the song and after x number of plays of normal playback,
PT will decide to suddenly mute one or more tracks that previously played.

Switching off automation option to "off" and back to "read" fixes it while it's playing, but not the next time it plays.

I have tried different automation thinning options, and most of the Windows 7 optimization/troubleshooting tips to no avail. This only started happening recently ( after a year of using PT 8 on my Lenovo laptop) & affects all sessions at on time or another, but I can't pinpoint any thing that would have triggered this problem. I updated to 8.0.5 and no difference. It happens in sessions with PT supplied plug-ins only.

windows 7, 4GB ram, Mbox 2 mini PT 8.0.5

Any help would be appreciated, I'm close to not being able to use PT at all.

[albee1952]

Trashing prefs and database files is step one for any odd behavior. See the General Troubleshooting thread

[peemarl]

Thanks, but I did all that. Just as bad as ever.....