User Verification problems ?

Have recently installed this plug in onto my site, and now when an advertiser tries to post an ad, all the category fields don't show in the submit form?
Also when a new user tries to join, there are problems there too...verification emails sent to new user, and admin of site, but when the password is entered, nothing happens and the user is told incorrect password?? Users also have to be "authorised" prior to all this.
Can anyone help with these issues, or can you tell me honestly, that if I deactivate this plug in, everything will return to normal?
I have just spent two hours putting all the setting back to what they were, and still am having issues. Grrrr