Even though I really like Cometchat, it seems that the server problems starting around the time I installed Cometchat.
I read various discussions on the web complaining that Cometchat sometimes bogs down servers, so I've been watching it closely. The server load was still very low, so I thought everything was okay, but this was too much of a coincidence for me.
I also found that the server was having a lot of memory allocation errors, which I'm not sure were happening before, because it's the first time I checked the error logs.
Bottom line: I'm going to leave it off for awhile, and see if things improve. If they do, and I can't find the reason that Cometchat was causing these favors, we're gonna have to do without it.
Please let me know if you still see the server errors.