[Darryl Ramm]

This seems pretty unusual.

Have you been careful about testing at the same IO Buffer size, sample rate, and sample depth? also try trashing prefs between tests, and make sure you are doing that fully correctly for your software versions... and/or use a utility to help.

I would not assume it is a memory conflict or anything Windows system level utilities will be able to identify. If you can reproduce this the best place to take the problem is the plugin manufacturer. They are in the best situation to debug what is going on.

If you wanted to push to the ultimate test, do a clean install of Windows and install just Pro Tools, ILM land the Eleven Rack driver and that plugin and see if it has the same problem.