On my system, MemoDB.pdb and MemosDB-PMem.pdb have exactly the same textual content (as per strings), with different binary formats. I can reproduce the error message with the latter file, but the former works. My understanding is that the latter file is from newer Palm versions, and I guess it's possible that if you have a newer Palm, you only have MemosDB-PMem.pdb? In that case, sorry, I'm not sure where to go from there, Google results are pretty thin. Have you tried J-Pilot? As far as I can tell from the source code, it can read both formats.