I'm coming across a very annoying thing with ISA 2006 with OWA FBA. Every so often, the OWA Forms-Based Authentication screen on ISA 2006 would just stop responding to requests where IE7 would say "Internet Explorer cannot display the webpage". I monitored this, and I can see people are reaching ISA 2006 through HTTPS, but it just establishes and closes the connection. After a while the OWA FBA would start working again.
I've installed the Supportability Update hoping it would fix this, but it keeps happening.
Is anyone experiencing the same thing with ISA 2006 with OWA FBA? If so, what's the fix for this?
Assuming you really mean the FBA *on* OWA: passing anonymous requests through ISA and having the OWA server do authentication? Yikes, not a best practice to say the least. The ISA FBA integrates nicely with OWA and is more secure. Using that approach instead wouldn't establish the cause of your problem but it would make it irrelevant by turning off the owa fba.
On the other hand if you meant that it's the ISA FBA has the problem: I recommend opening a MS support ticket. The ISA support engineers have some pretty great tools and expertise to troubleshoot. Since your problem is intermittent, it seems likely it could be a bug of some kind. If that turns out to be the case, they won't even charge you for the ticket. (Otherwise worst case it's like $300, big deal..)
I'm not too sure either, but I think I'm doing the latter. I did an Exchange Server Publishing Rule using FBA Integrated authentication to reverse proxy to Exchange for OWA, making ISA 2006 the front-end. I have FBA turned off on Exchange.
Like you said this intermittent, and there doesn't seem to be any warnings or errors in the event log. OWA does work on Exchange when this happens as we are able to bring it up internally. I wonder if it's a hardware issue? We do only have 512MB of RAM, which does show up as something with ISA Basline Analyzer.
By the way, this may sound like a newbie question, but how do you open an MS support ticket?