I got the dreaded above-named error tonight. Fortunately, a quick trip to phpMyAdmin at my hosting provider to do a check, repair, and optimize fixed it and all is back to what passes for normal.
I use GoDaddy. Their tech support is superb, and I say that as someone who wore a headset for six years.
Addendum, the Next Morning:
This morning I got a MySQL socket error. I ended up rebooting the VPS and everything seems to be working again. If you notice any wackiness, please drop me a note via the email link over there on the sidebar. —————->