MS Search Service Instance refused to come online in Clustered Exchange Server

You will see Event ID 3055 and 10006 on your Exchange cluster node. In Event Id 10006, you will also see this error message: 80070002 - The system cannot find the file specified..

When this occurred to me I simply restored the search service files to the original location and that resolved my issue. I was able to make the search service online again.

For rest of the details follow this MSKB: http://support.microsoft.com/kb/310586