DCOM problems

[renfri]

Have a setup of 4 servers running SBS 2003. One server is the SBS server, one is the SQL server, one is the TermSvr, and one is the backup server. We have 19 PC's running XP connected with RJ45. We just upgraded to this setup. I am getting DCOM 10006 and 10021 errors. The 10021 error says that "The launch and activation security descriptor for the COM Server application with CLSID
{2A6D72F1-6E7E-4702-B99C-E40D3DED33C3}
is invalid. It contains Access Control Entries with permissions that are invalid. The requested action was therefore not performed. This security permission can be corrected using the Component Services administrative tool." The 10006 error says "DCOM got error "The RPC server is unavailable. " from the computer 192.168.0.17 when attempting to activate the server:
{8BC3F05E-D86B-11D0-A075-00C04FB68820}" I did some research & found an article saying to go to Component Services and add Authenticated Users and then one said to add Network Service. I have done this & still getting error. Does anyone have any ideas. THX!!!!