MENTOR DC Drive goes goofy

Hello,

We have MENTOR DC Drives (7 years old) with interbus link to PLC.
Sometimes (1/week) the drive goes goofy

*) weather flipping off with unreferenced error code
*) weather changing parameters values
*) weather starting by himself with a speed reference coming out of space, impossible to stop except by Estop shutdown.

The crazy thing is that we changed the drive and control board and network board several times and the probles remains.
Reloading parameters with an old backup does not help.

Did somebody experience things like that, any tip on mentor is welcome, place to find support,...

Thanks

Antoine

Mentor is a product of Control Techniques Here is the page for Mentor Drives. http://www.controltechniques.com/products/products_frame.htm?dc_drives.asp&mainFrame

On their home page is a listing for support. The phone techs are pretty good. I have never seen the problem you are having but we are using this drive in an open loop system.