Fairly new to WP, but getting better, I thought. Just upgraded to 3.0.4 from 2.something. Automatic install seemed to work perfectly - my modified BlueLeather theme seemed to handle things well even though it is no longer supported at themeforest. But then I noticed the category pages that collected and displayed posts in particular categories no longer display - just blank white pages, no error.
For example...
http://www.sitename.com/category/photography/ used to display all posts in the photography category. Now just white. Tried sitename.com/photography etc. and no luck, just white page with no error message.
All posts can still be viewed directly by permalink. All categories appear to still exist in admin as they did before the upgrade.
Somehow WP or my theme(?) is no longer pulling together the category pages?
Any ideas what to look for to fix this? Any suggestions are welcome.