I just setup a new SBS2011 x64. All OK.
Installed all windows updates. OK.
Installed Visual SourceSafe 2005. OK
Installed Visual SoruceSafe 2005 Update. OK
When I run SourceSafe Administrator, and enable SourceSafe Server Internet connections, it creates the SourceSafe Virtual Directory in IIS, then IIS crashes.
IIS then constantly crashes (several times a minute).
After some hours of fiddling, gave up and blew the server away. I repeated the whole process again and it destroyed IIS again.
(this time, I took bare metal backups of the server between each stage - 20 minutes to restore, not 4 hours ;)
Seems to be caused by the line in C:\Windows\System32\inetsrv\config\applicationHost.config being changed by VSS from:
Changing it back brings IIS back online immediately.