Component Services, SSIS, Event Log error

Regarding this question-and-answer:

http://social.msdn.microsoft.com/Forums/en-US/sqlintegrationservices/thread/3801bf04-71da-4471-b777-21bb236204ff/

how did the questioner know from the CLSID and/or APPID to look for the  MsDtsServer100 entry?  We have a similar error (below) and I was wondering how to figure out what those two IDs referred to.

I don't see those IDs or MsDtsServer100 in Component Services either. In the previous question the reply was to re-install SSIS. Can SSIS be installed after-the-fact on top of an existing (running) SQL Server installation without doing any harm? Or should the database be stopped during the SSIS install?

Thanks

The application-specific permission settings do not grant Local Activation permission for the COM Server application with CLSID

{FDC3723D-1588-4BA3-92D4-42C430735D7D}

and APPID

{83B33982-693D-4824-B42E-7196AE61BB05}

to the user NT SERVICE\SQLAgent$SQL2012 SID (S-1-5-80-4208878284-2110494983-3369860648-438030004-2611322830) from address LocalHost (Using LRPC). This security permission can be modified using the Component Services administrative tool.