Okay, here it goes:
Have a guy with this problem:
Pentium III at 900 MHz
OS is Win2000 SP4 Rollup 1
No other AV, firewall or anti-anything software installed
AIS installs fine, but firewall can not be startedI did everything that we normally do: repair install, reboot, uninstall utility, ran MBAM to see if any malware might prevent the start, install without network cable etc, etc... to no avail.
There are no errors, all works fine, except the firewall won't start and the "start" and "stop" buttons on the firewall tab both look the same way (enabled style).
I only have email contact to the guy and he speaks no english at all.
What do I do now?

He's getting angry, and I can understand that - he already paid for the AIS :'( (even though I think you always should go with the trial first, but... alas! he did not)