I've only been mining for about a week now, and I occasionally get the following error/crash:
Assertion failed!
Program: D:\Primecoin\primecoin-qt.exe
File: src/checkqueue.h, line 171
Expression: pqueue->nTotal == pqueue->nIdle
primecoin-0.1.2-hp9-winx64.zip
It's a bug in the primecoin client - It's been partially fixed but everyone gets it occasinally. From what I have heard systems with more cores (6+)tend to get it more often. All we can do is just restart the primecoin client to deal with it for now.