Page links all go to homepage

The links to my posts work fine, but the links to the pages all go to the homepage. Last week I was able to fix this by setting the permalinks back to the default, and then to custom again. But now that won’t work.

I tried deactivating all plugins, and switching to the Twenty Ten theme, but that did not solve the problem. I tried deleting .htaccess and having WP rebuild it, but that didn’t help.

It seems to be a problem with permalinks, because the default permalinks work fine. But I want to keep my permalink structure, which is /%category%/%postname%/. My thought is that maybe something changed in 3.4 and WordPress chokes on this because pages don’t have a category. But that is just a guess.

The strange thing is that I have another WP install with the same permalink structure, and that is working fine.

I upgraded to 3.4.1, but that did not fix the problem.

Any suggestions?