Forum module issue: Lack of link/correlation between Forums and taxonomy/vocabulary:

I was able to determine that my site was not working right, using another install of Drupal. Forums automatically created the appropriate vocabulary and terms.
Also posting to a Terms corresponding to a forum "container" did not give an error message, like it should.
Running Drupal Beta 6 (but been having this problem since Beta 3?). I think, I might have even caused this problem by deleting the Forums vocabulary before understanding what it was (and simply recreating this vocabulary did not full fix the problem).

Here is what I did to correct this issue.
First delete everything related to forums on my site using the GUI. Then disable the "Forums" module.
Finally, in the table "variable" deleted all entry starting with forum_ (like forum_containers ....I think I deleted a total of 5 records).

Note this is not the first time, that to get a module to work properly again I had to delete the entries for that module in the "variable" table. So I would guess, as an additional nugget of information,  that this could be a good tip in case it looks like another module is not working properly and needs to "initialize" again. In other words looks like many module say: "If I already got some of my variables set in the "variable" table, I've been already initialized...so I do not need to initialize anything...".
 

Note: Since I was using the PathAuto module, I had to cleanup all the invalid URL aliases, creating during this troubleshooting....