bed mintemp error  

bed mintemp error

I posted this in the 'printing' forum but I think it is some kind of a hardware problem. I've been printing without a problem and the other day when I went to print a new object it stopped while it was trying to do the bottom layer with a BED MINTEMP error. I trtied it again, same problem. So I tried the prusa-logo [my go-to test object] and I got a similar thing but it didn't even make it to the bottom layer. Now, when I try to print anything the printer does the nine z measurements, slews to the near left corner. And then stops. The extruder fan speeds up for a little while but then everything shuts down with a BED MINTEMP. The room's ambient temp is around 68 F so I would think it would be a problem [and ahsn't been a problem for the dozen or so prints I've done already]. Any advice on what to try/check? Thanks