I have data on a 1TB Hitachi Portable. (a tested and perfectly working drive formatted with
HFS+)

I have tried transferring 15 GB of this onto a Transcend 32GB Flash drive (formatted with HFS+)
Transfer seemed as if it went ok.
Went to open up files - a lot of them were not opening up.
Double-checked with original medium (1TB Hitachi) - files opened up fine.

TAKE #2

Assuming I was transferring onto a duff 32 GB Transcend
I used a brand new 32GB Kingston Flash drive instead (native formatting)

Outcome: same result. A lot of the files have appeared to have copied over but when you open them
they are blank.

I am puzzled and need help on this one?

Hi, I take it you are doing this on a mac?
I am not as familiar with them as I am with a Windows PC, but the first point of call I would do on a Windows box is go through the eventlog looking for errors.

ths link may help you to watch the system as it is transferring, or at least see if anything shows up after the fact:

https://discussions.apple.com/thread/25 ... 0&tstart=0

Another possibility is write cache, again you would have to research it, but it may take a lot longer for the system to write everything on there than you think, meaning it may look as if the files are finished copying, but in fact they arent.

does this mainly occur when you try and transfer a large amount of data, or also if you do a few hundred meg as well?

hope that helps..