Troubleshooting 64 errors is always fun. All you know is that the "host not available" isn't much help. However, you can take advantage of the ISA firewall's advanced logging and troubleshooting features to solve this otherwise difficult to trouble problem.
In this article Yuri Diogenes shows you how he solved a 64 error for a Web Publishing Rule. Check it out at:
Thomas W Shinder, M.D., MCSE
Sr. Consultant / Technical Writer