Bad unit or cards?

[hardlock]

I've had a chance to get familiar with my BR and am now getting lots of read/write/busy errors and lockups.  Thought I was the cards I'm using (2GB SanDisk Ultra II SDSDH-2048-901 and a 512 Kingston).  Even the factory card does it however. 

Playback is fine but most recording, bouncing, mastering, and editing causes trouble. 

It all started with what may be a corrupt track (is there such a thing?)  I had punched in and out a couple times to erase some mistakes of one side of a stereo track and later tried to add the corrected parts in the "holes" (Recorded 2 stereo leads and wanted to mix each as left and right together into a new stereo track). 

Weird things started happening like out of sync playback of punched parts, disappearing original track when bouncing with no track being recorded from the bounce, terrible static noise instead of music on one side, etc.

Tried optimising, initializing and restoring from backup, same things end up happening.  Totally random and very frustrating.

I'm at a loss but love the BR when it works right.