Okay, I managed to solve this one, but I haven't seen anyone else mentioning this solution anywhere: hopefully my solution can help someone else.I should mention that I have a multi-machine deployment, windows server 2008 R2, IIS 7.My IIS event log was spitting out some DCOM garble, as a few other people had mentioned in their posts:The application-specific permission settings do not grant Local Activation permission for the COM Server application with CLSID {379376DB-AEA6-40D1-9491-9345E61EF6BE} and APPID {E0C11371-7FDD-4633-9529-A8C4E4BD01ED} to the user IIS APPPOOL\ArcGISApplicationsAppPool SID (S-1-5-82-1428824514-3347186755-1149792753-598056336-1244538121) from address LocalHost (Using LRPC). This security permission can be modified using the Component Services administrative tool....anyhow, I looked at the Advanced Properties of the ArcGISApplicationsAppPool in IIS, and changed the account it was running under to be my SOC account. This solved it. So, E0C11371-7FDD-4633-9529-A8C4E4BD01ED relates to the SOM and in fact the only thing not working was ArcGIS Server Manager the identity of the app pool which Manager runs under was being denied somewhere, probably the arcgisserver\cache or output folders...The annoying this is that really, I just did everything standard straight out the box.... if the Post install isn't granting the ArcGISApplicationsAppPool's identity the necessary permissions, then how will Manager ever work (think this is IIS 7 specific granted).Anyhow, enough rambling, back to work.... how do I mark my own posts as answered??? - oh, I see, the new stack overflow arrows.
