In my case, I was running Server 2003 (32-bit). There is a registry folder located at "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Search\Gather\Windows\SystemIndex\Protocols" that belongs to OneNote, and if you uninstall OneNote uncleanly this reg key will produce the error. Solution is to reinstall/repair OneNote, or if it is uninstalled backup the registry and then delete the folder.
Error description: The specified module could not be found. (HRESULT : 0x8007007e). - See the comments for Error code 0x8007007e
Error: Class not registered - From a newsgroup post: "This was also an issue on 64-bit Vista and we made a fix for it but it looks like the fix did not correctly address 64-bit XP. The background on this issue is that there are two processes that can index on 64-bit machines. One process is 64-bit and can load 64-bit protocol handlers and the other is a 32-bit process, which can load 32-bit protocol handlers. In this case, since mapi (which is used to index outlook email) is 32-bit only when the 64-bit protocol handler process starts it tries to load the 64-bit version of the non-existent mapi protocol handler. It should call into the WOW64-32 layer to determine that this handler is correctly registered in the other CLSID hive and not display the error. For some reason this check is not passing most likely due to some incompatible vista only flag we are using when calling to WOW64. The good news is that this error message will not affect email indexing but will create event messages every time the protocol handler starts up". See the link to "Windows Search Service error" for the original post.