Korg T1 - "Data Error"

I replaced the lithium battery in my T1, and tried to reload the factory sounds. When it gets to load PCM data, I get a "Data Error" on the LCD display.
The manual says this is a disk problem, but I've tried several known good disks and still get the error.
Is there a hard reset key sequence? Any other suggestions?
Thanks.

I'm having same problem. I didn't recently change battery but I had my disk drive cleaned out after a toddler put a ritz cracker and a paper clip in the drive slot.
The technician cleaned and checked it and it functioned well (at least mechanically).
Now when I tryed to save a sequence to disk, it goes fine until the end of saving (after "saving PCM data") then it displays the "data error message".
Please help.