I have the EXACT same problem as Feekh: (happened in the EXACT same manner)
QUOTE(feekh @ Dec 5 2006, 05:52 PM)

After some months of playing backups with my hitachi flashed drive (flashed with birdy flasher)
it suddenly stopped!
Was playing test drive and all of a sudden the game stalled..
My xbox has never played a game since. Backups nor originals
I have Hitachi DJ47 with GaryOpa 2.1 firmware. 90% of backups no longer work giving various errors "unrecognised disk", "open tray" etc.
Some originals work, some partly i.e. load and then get dirty disc error, some not all all.
I'm going to try the following:
1. Flash firmware with latest GaryOpa 2.3 (has 2.1 on currently)
2. "Rubberband Mod"
3. Pot Re-Calibration
Failing the above I see no other choice but to get a replacement drive or laser assembly.
Can anyone out there suggest a solution before anything drastic is done ?