That's difficult to say / debug remotely. It looks like the IIS process is not able to start. This could a security issue, a performance issue if it takes too long to start up, or a configuration issue (wrong patches, service packs etc). Is the Windows event viewer telling you anything more?
If I
search Google for the error, I get a number of results, with different causes and resolutions. Maybe you recognize some of them?
Imar