To correct the error base

To correct errors in the database dle, possibly after upgrading dle, there were these problems:

1. does not the registration of users during the registration to the end of registration appears Access Denied! and the user can not go, although in the admin I see it but to remove or something to do with him, says "This user is not found."
2. when switching to one of the categories, there was an error Service Unavailable
3. search sometimes throws an error Cant find FULLTEXT index matching the column list

I think its the same reason there is no coherence in site basis