Close LR and try deleting your previews folder that is beside your catalog location.
It will be called something like- "Your Catalog Name Previews.LRDATA" CAUTION: Do not delete anything else!!
Restart LR. The previews will slowly re-build so you may see some temporary slowing.
Well my friend thank-you and worked like a charm, Its very comforting that this now works again...THANX ever so much..
Mike / Your the best..