used the Toshiba 60GB drive to upgade a friends Z1 to a Z3. IT seemed like the writing of the drive took a bit longer than the others i have done but it said it was sucessfull at the end. I get a call two days ago telling me it now wont boot at all gives some message stating "HDD Unable to boot" or something like that. He said it was doing it it from time to time before and cycling the key would fix it and now it wont boot at all.

will a rewrite cure this or is it a faulty drive?

It could be either. I would try to reimage the drive first, and if that does not fix the problem, then RMA the drive. The drive should still be under warranty.