meck: the MBR itself seems to be clean (at least according to the mbr.exe output you posted).
Sector 0x12a14c00 may contain some shyte but it shouldn't get activated.
Seems like somebody already tried to disinfect the MBR rootkit, and wasn't quite thorough...
Anyway, are you saying the system doesn't boot?
Also, what does this have to do with a pen drive?
Cheers
Vlk