File server suddenly stopped working

I have a file serverthat suddenly started having issues last week. Users were unable to checkout/add to workspace, checkin objects to it. Also, the replication schedule started failing as well. To date, PTC hasn't been able to determine what the problem is either. The one constant is an error message in the MS logs that says:

ERROR : wt.wrmf - Execution problem for Method remotePullAndStoreStream in given class wt.fv.replica.StandardReplicaService
Caused by: java.lang.NoClassDefFoundError: Could not initialize class wt.fv.FvProperties

Does anyone know what this means? I can't find anything about it in the PTC knowledge base. And there is no reference to the wt.fv.FvProperties file in the wt.properties file. It's not referenced in the wt.properties file on my other file servers, which are working. Does anyone know how the wt.fv.FvProperties file is intialized?

Thanks in advance! Dave