Why can't I load thumb drives?

Hi

Basic question, probably.  I have about 400 MB of flac files on a hard drive in a windows computer.  I have, in the past, transferred the whole thing to other hard drives with no problem.  But when I try to load into a thumb drive  the transfer bogs down and stops.

A friend tells me that memory chips are no good in this capacity.  Is this true or is there something I can do to effect the transfer?

Bill