Nifty, I get that error every once in a while. I'm not searching for anything. My bookmark is set to the "Recent Posts" tab. So I guess it is searching for recent posts. A refresh will get it by most of the time.
Rarely, I will refresh a couple of times and keep getting the same error. I just do something else for a couple of minutes and come back & it works.
I figured maybe it was an issue of too many people trying to access the site at once. It hasn't so far been enough of an inconvenience for me to even mention.
* I didn't know it wasn't supposed to happen. Got it twice last night and once this morning. All red and kinda pretty. Just though I'd blundered into a "closed door" or something. Sorry, Nifty.