OK, I figured this out. It was the &showposts=4 that was causing problems. I removed that and everything worked fine!
Thanks for the tip!
It doesn’t solve my problem though. ):
It’s the presence of the &paged=(>1) in the url that’s giving the 404. I’m trying to figure out why that is, and if I can get it to work.
For example http://mysite.com/?cat=6&paged=1 works fine. But, http://mysite.com/?cat=6&paged=2 gives a 404 error.