WinFax Pro

My OS is Winxp pro with SP2 with WnFax pro v 10.02
I manage to get it up on all client to link.

My internal modem is prolink 1456PVC..
While is it sometimes the software just hung while receving fax.. and i need to restart the winfax pro for it to continue receive fax..

Why is it so unstable??

Please help