Post Categories and Tags broken

Yesterday I uninstalled the WordPress Stats plugin and removed it from my site (I didn’t want to install Jetpack) and I installed WP-Slimstat. Everything seem to be fine, pretty sure I tested out the admin settings of it and the front side of the site was working fine.

Then when I visited my site today, I noticed when I was writing a new entry that Post Tags weren’t saving anymore. When I try to add a tag to the article, it looks like it is added but when I hit Save Draft, all of them are then cleared. When I look at all my posts in the Admin it looks like ALL the tags for all the posts have been removed. (Also have a tag cloud and it shows the correct number of uses for each tag but when I click on the link to see those tags no results show up).

Similar issue with Categories, looks like all of them got removed from all the posts. Clicking on the Categories option in the Admin confirms that. All the Categories I once had seemed to have been deleted.

Other than doing the uninstall of the old WP Stats and installing this yesterday, I did nothing else until this morning. It is though some how certain parts of the database got messed up overnight? Could this plugin have anything to do with that? Or know of any other suggestions that come to mind?

Thanks a bunch!

(I have posted this in the plugin forum but still waiting on a response from the author. So I figured I would see if you guys had any ideas from a more general WordPress side of things.)