fyi, I found the problem, here's the resolution...

IP Address Mapping

Reporting Services requires that the default Web site IP address is mapped to (All Unassigned). To verify this setting, open the Default Web Site Properties dialog box in Internet Information Services. The IP address is specified on the Web Site tab.

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/rsinstall/htm/gs_installingrs_v1_8k82.asp