HP Issue?

Hello, I have an HP fax machine and I can't seem to fax the complete document to my pFax. Most of the times I will receive half a page or fail transmission. Does anyone has the same issue? Can someone else advise or show me how to correct this? I contacted my fax service provider (WinFax), and they can't seem to know what happen. I send fax from another machine and I receive just fine.

Thank in advance.

Todd Thomas