We have about 150 or so 180's in the field and we have replaced about a third of them so far with 190's.
A factory default fixes them occasionally but we have found them unreliable lately. You could try rolling back to 2.6.2.1 to see if that fixes it, we had no problems with that firmware but are unable to roll our entire network back.
edit: we first started seeing reboots on 200's and 180's with 3.0, we are currently on 3.5