The problem may be what it says, the document is open in another application. Is your pdf on a server? Are you working with the original extended pdf or a copy? Try this:
1) Make a few extra copies of the pdf in Windows to work with.
2) Can you sign a copy of the pdf in Acrobat using your Topaz Signature pad?
3) Can you sign a copy of the pdf in Reader using your Topaz Signature pad?
Do you have any background processes going on? (Automatic backup, virus protection, etc.) If so, can you try to halt those processes?
No, the PDF is on my local machine when I open it and try to sign in Reader. I'm working with the original extended pdf.
2) Yes (and this has always been the case).
No background processes that I can think of. Also, we've gotten these same results on several machines.
For some reason, I have a feeling this has something to do with the fact that it's a form created from a Word document. In the Googling I did before coming here, many (if not most) of the people who had the same problem said that theirs was a form created from a Word document. And on every single one of the cases, the people responding either didn't address that fact or didn't seem to think it was relevant. But could it be??