Stylehack

If you recently upgraded to WordPress 2.6 and suddenly your pretty permalinks don’t work properly, or at all… and if your “more” or “page” features aren’t working (usually a related problem), there is a temporary fix you can put in place:

http://wordpress.org/support/topic/189058

Basically, look at #2 there. I’d try it in two versions:

1. First, without “/index.php” added to the beginning of /whatever-your-existing-structure-is/ AND with “category” and “tag” in the two custom fields;
   
   
2. If that doesn’t work, add the “/index.php” to the beginning of /whatever-your-existing-structure-is/ AND leave “category” and “tag” in the two custom fields.

My experience is that adding the “/index.php” doesn’t hurt even on an Apache server, and in some cases solves a world of hurt.

Notice I said “temporary fix”? Quoted directly from the support post above:

The upcoming release of WordPress 2.6.1 will correct this issue.