I'm looking for an alternative to pfSense (2) that can be virtualized in VMWare ESXi. I've experienced several problems with pfSense to date and I feel like it is not a totally finished or polished product. Whenever anything goes wrong (IP address conflict, squid misconfiguration, etc) the whole thing goes berserk and it takes a reboot or at least 5 - 10 minutes to fix itself. In many cases even resetting state tables does not help and only serves to compound the issue.
I think part of the problem is that I probably really suck at pfSense, being new and all, but I've never had this many problems with a firewall appliance and this is coming from a background of using Checkpoint and Linksys and even the occasional D-Link. Of course we run all of our stuff off Cisco ASA at the moment (physical hosts, at least) and I wish I could just run ASA in VMWare but sadly that is not possible.
Please provide any recommendations for either a) guidance on getting pfSense stable, or b) other virtualizable firewall appliances.