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[Macro]

i have same problems before, try following:
1. remove the mysql root password,
2. just hit enter after update ask you for root password.
3. if success updated to rc6, change your mysql password back,
4. Change ispcp db password (step 4-6 of http://www.isp-control.net/ispcp/wiki/howto_dbchangepw)

ps. i use http://ispcpaddress/pma/ to change mysql root password.
try it, work for me and now running rc6 ;D