This doesn't seem to be a problem elsewhere, so sounds site-specific. Maybe you have another application on these servers that has downgraded the log.dll file to an older version or there are multiple versions on the hosts and regsvr32.exe has the wrong dll version registered.
You could try to use Sysinternals' ListDLLs to see if it is loaded already from somewhere, or do a registry search to check if/where the DLL is registered. I would search the entire system drive for copies of log.dll, and if there is an application with a local version in it's program directory, it might be your culprit.
