My fax software is "iffy", i.e., sometimes I'll get a fax, sometimes I get "An error occurred while receiving the fax". What to do?

fxservices is running, but, just the same, I stopped it and started it. Still getting the message. I’ll probably have to reboot my computer to get it to work. Meantime, the faxing party already tried four times. What can I do to ascertain I get the fax first time, everytime?

I use Windows XP with the Windows fax application.