beta testing the next version might be useful to someone, but it doesn't sound like it will help anyone having immediate problems with 9.1.507.000
For me, this latest update simply will not fully install, and while installing, somehow all of my restore points were erased as others have mentioned, so I could not step back to a pre-install point.
It seems to be going fine up to the 16% mark, where it is copying zlquarantine.dll ...and then it simply freezes. It has done this every time, so I will be yet another talking to technical support on Monday. I am logged in as administrator on my XP SP3 auto-updated machine, so permissions shouldn't be an issue.
It is a bit of a pain that I have just paid my annual subscription (361 days left) and now have no Zone ALarm installed at all because an update is screwy (the old version 9.1.008.000 does not recognise my licence key from the purchase receipt).