Hardware and performance

Hi
We are running 1.7+ and lately it has been running frustratingly slow. Seeing that things couldn't get any worse I decided to upgrade to 1.8 beta - thinking that this might sort out any database problems. However the upgrade stalls and gives the following message


1062: Duplicate entry '1-kh8866' for key 3

adodb_mysql._execute(CREATE UNIQUE INDEX mdl_user_mneuse_uix ON mdl_user (mnethostid, username), false) % line 889, file: adodb.inc.php
adodb_mysql.execute(CREATE UNIQUE INDEX mdl_user_mneuse_uix ON mdl_user (mnethostid, username)) % line 89, file: dmllib.php
execute_sql(CREATE UNIQUE INDEX mdl_user_mneuse_uix ON mdl_user (mnethostid, username), true) % line 1899, file: dmllib.php
execute_sql_arr(Array[1], true, true) % line 1080, file: ddllib.php
add_index(Object:xmldbtable, Object:xmldbindex) % line 342, file: upgrade.php

ErrorScroll to next warning

Scroll to previous warning Main Upgrade failed! See lib/db/upgrade.php


Scroll to continue button


Is anyone able to advise me how to fix this problem?
thanks
kathy