Interesting case study on a TMG firewall that stopped processing web requests:
“My customer had a TMG array with two nodes running with NLB. The problem they faced was that from time to time some TMG node couldn't process traffic anymore: requests to the virtual IP (VIP) failed and only rebooting the TMG machine eliminated the issue.
IE was configured to use the NLB virtual IP (VIP) as proxy address. When the issue happened users couldn’t browse internet pages - the browser didn't show any error page, it just stayed with a blank page…”
To see how they troubleshot this issue and a solution, check out:
DEBRA LITTLEJOHN SHINDER
MVP (Enterprise Security)