The search index could not be updated. The site is misconfigured. Contact an administrator. SQLSTATE[42000]: Syntax error or access violation: 1064 unknown table 'tiki_main_67970848c9392' in delete request
Maybe the 1.8.2 installation went through partially and changed your database (i think it changes it enough that you can't simply dump your tiki 1.7 database back in). I would delete the database, re-install tiki 1.7.x and then put my database dump from my former 1.7 installation back in the database that was setup by the new install. But maybe someone else has a more elegant solution.