after you upgrade your mysql server you need to run MYSQL_UPGRADE to check for problems in your tables.
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dev.mysql.com]
what version of WAMP did you upgrade from? the current wamp 1.6.4 comes with mysql 5.0.22. According to mysql, when upgrading a 5.0 installation to 5.0.10 or newer, it is necessary to upgrade your mysql user grant tables. Otherwise, creating stored procedures and functions might not work.