JimH -
This has become a saga. Uninstalled DFX, no joy. Did a dumb, lazy thing and tried reinstalling 256 over 257 - sadness.
Uninstalled 256, ran Norton Win Doctor to confirm there were no tag ends lying around from either 256 or DFX, optimized the registry, rebooted and installed 256 which used to run without a hitch. Couldn't access normal Play mode (ctl-alt-del followed by Reset to recover)
After numerous reboots I tried Play Media File and everything seemed OK. Closed MJ and restarted, Play functioned properly. Closed MJ went to check how my life was doing came back brought the system out of standby, started MJ and lockedup when I tried to Play something.
It is now several reboots later and I cannot get 256 to Play at all. Next step uninstall 256 and revert to 248 which was very stable for me. I'll report back on the results.