Hi Katiesue,
I've transfered files from my computer to a Gen3 and it has worked without a problem.
So I'm guessing what has happened in your case is either that Word has exported some hidden formatting that the Gen 3 doesn't accept (Word is prone to causing problem like this when exporting to other soft- and hardware) or maybe the pdf created by Word isn't Adobe compatible. Or both.
Something to try:
Type some documents in Wordpad instead and save them as .txt or .rtf. Those formats shouldn't be any problem for the Gen3 to read.
There's also a lot less possibility for some strange code to be generated in the process.
If you have
Atlantis or the means to get it you could even make epub-documents for the Gen3. But that means you have to upgrade the ereader first.
Good luck,
Mange