Well, IMO, if the flashdrive works in the Win 7 64bit desktop but not in the Win 7 64bit l/t the problem is with the l/t not the flashdrive. It could be a Windows 7 setting or one of the l/t’s 30 trial security apps causing the problem.
You can format the flashdrive if you want but other than loosing 21 yrs worth of files I don’t think it will solve your problem.
If you find a solution let us know.