In the afternoons and evenings I sometimes get a 'Site is busy. Please try again later' message. I just hit refresh a couple of times and it usually comes right up.
Hmmm, this site is running on a VERY fast server (dual Xeon processors), so that does surprise me. Of course, I do have a couple of other very active message boards running on the server as well. Maybe it's getting time for me to move some of the utility functions onto their own server.
I have seen the statistics programs sometimes running at peak traffic hours, which definitely gums things up, so maybe that causes the problem. I'll see what I can do about moving them to a different time slot.