VNETSUP ERROR 6107

Registry errors
Out of about 5 machines we have 2 that come back with an error vnetsup registry needs to be restored. All 5 of these machines have basically the same hardware. If we restore the system.dat with a backup we made when the machine wasrunning, it will usually run 2 or 3 days and blow up again. Formatting and starting form scratch doesn’t always help. After installing 98 the vnetsup error went away but we still get a registry corrupt message and 98 tries to restore it. “Windows networking could not setup instance data error 6107 VNETSUP please reinstall windows.”
Any help would be appreciated