Can't add menu items after deletion of Category Item

Hi,
This may be a bit of a newbie kind of mistake. I originally added the Categories Module because it sounded like I would be able to create categories for the products on the web site I'm building, and those would in turn affect the menu. I'm building a new web site for an electronics test equipment company that has a lot of products. Anyway, I could never manage to magically make the categories I created link into the menu items so I gave up and went to taxonomy to create the ways I would/could sort the products based on model#, application, platform and function. I initially created the platform vocabulary in categories but gave up on it when I couldn't get it to do what I wanted or thought it was supposed to do. So I then created all the vocabularies in taxonomy forgetting about what I had done in categories until yesterday. I had linked up primary menu items to the taxonomy and everything was working as expected. I started adding additional products and got the great idea to delete what was in categories to clean things up. Mistake! I don't know exactly how I did this. I don't think any of the menu items were linked to categories but I think I may have been wrong about that, or I made a mistake and the products had identical naming in categories and taxonomy. Anyway, when I deleted this "By Platform" category it broke my drop down menu.

The links in the dropdown menu work but there were initially 3 items that would give me secondary drop down items... ie.... "by application" would give me a listing of "legacy, precise timing, etc.", and "by Platform" would give me "VXI, PXI, LXI, cPCI, etc.". Anyway, when I deleted the category item it deleted the "by platform" sub menu and raised all it's entries up a level into the main product directory menu.

None of the taxonomy vocabulary changed which I thought I was linked to but maybe not. So I thought I'd try to recreate the "by platform" sub menu and then rearrange the primary menu items so they would once again appear like I wanted in the main product drop-down menu. I can't do this. I get the error message of, "The path 'content/products/by-platform' is either invalid or you do not have access to it."

I next tried to disable all the category module items thinking this may be clear up my problem. Nope, got the same error when trying to create a new menu item. I next completely removed(deleted) the Categories Module from my server then ran update. Same result.... same error message.

As I'm in the initial phases of developing this site, I hadn't backed up the damn thing so there's no going back for me. I'm at the point now where I'm thinking I may have to completely wipe the database and drupal install and start from scratch. This of course sucks as I've done quite a bit of work. But if I can't fix what I somehow broke then I guess I'm screwed.

I thought I had a better grasp of the differences between using taxonomy and categories, but I obviously don't. If you know of a place that does a good job of defining how they are different or you have an idea of who to fix this the right way let me know. Please... I obviously need some help here.

Thanks for your time, and help
Jeffrey