Very curious problem!
I have a PC with a fully-patched Windows XP SP2 and a Netbook with a fully-patched Windows XP SP3. Both had ZA Pro 9.1.507.000 installed on them and it worked perfectly (I love ZA!).
Today, I upgraded both the PC and the Netbook from ZA Pro 9.1.507.000 to ZA Pro 9.1.603.000.
The PC continued to work perfectly.
The Netbook (basically, a mirror of my PC, except that it runs SP3) immediately developed these issues:
(1) Programs opened very slowly and finally the Netbook froze and I had to hard reboot many times;
(2) I could not connect to the Internet. No way, no program, no connection, period!
I uninstalled and reinstalled 9.1.507.000 and everything's fine now.
What's the conflict? Is it between ZA Pro 9.1.603.000 and XP SP3?
Thanks for any ideas or help.