My site was working fine on Joomla 1.70, and out of nowhere, I noticed that clicking on weblinks categories did nothing at all.
• Disabled Joomla's SEF... started getting the "Category not found". Checked the numbers... category existed.
• I create a new category to use a weblink module that I downloaded, thinking that it was the J17 weblinks component that was wonky... couldn't get that page to display with a category blog.
• Hacked the Core as suggested... no effect
• Did the Enable SEF, enable joomla's htaccess, Enable URL rewrites and pages on site break
• Based on suggestions here, I upgraded (to 1.75) and still, same problem
• Not using JCE (although I normally do).
I seems that at some stage, something happens in the db and any category that you make after that (even in weblinks), is somehow corrupted. The only think I did relative to permissions was make a single menu item for registered users only, pointing to a jomsocial profile page. I disabled it, still in same boat.
I then started getting this strange
Warning: str_repeat() [function.str-repeat]: Second argument has to be greater than or equal to 0 in blah blah blah
in place of categories in the back end. At that stage, I started slashing categories and resolved the situation by deleting every category that wasn't working, and recreating them as well as the menu items that were broken. I also hit REBUILD icon in the category view after I did my deletes. Seems back on track.
Very disconcerting that a db can so easily be corrupted in 1.7. Praying that I'm not building a site on a damaged foundation.
So... my solution: delete the categories that aren't working, remake them with different named aliases, regenerate menus.