I have some Sony brand MicroVault USB 2.0 4 gig “thumb drive” I obtained several of these from a friend returning from China. After a couple of uses, the drive acts like a cdrom. The Sony software does not work on this drive. The Sony data sheet accompanying the drive shows it to be a model number USM4GU2. I have carefully disassembled the drive and found inside two identifiable chips. the smaller (probably controller chip) is marked as follows:
CREATE
I5062-ZD
L527
CE5615.0
The second and larger chip on the other side of the pc board is branded and marked as follows
INFINEON
1YF33DS512800ATC
SUU30529
p.s. For the first person supplying me with a working solution, I will send you one of these drives strictly as a token of my appreciation.