No recent AV/FW upgrades, other than defs; already ran through standard connectivity tests: cabling, NIC, router, drivers, etc., to include temp disable of AV/FW. Also ran scandisk on the host drives.
But, it turned out that it was quota related, after all. For grins-n-giggles, I went ahead and enabled/applied quotas on Svr and rebooted. Mapping was back up, so I disabled, applied, and rebooted...now good to go!
Who'd a thought? Guess its another of those nifty MS features! Will keep an eye on it, just in case.
Appreciate the look over my shoulder!