MySQL Query virtually killing my server (99% CPU)

[atinoco]

Greetings, I'm experincing an important problem here, eveytime one of my clients executes certain query to their database the cpu usage of the mysqld-nt.exe process jumps to 99% and all the other services (http, pop, etc) on my server freezes for a couple of minutes (while the query runs).

Is there a way to limit the resources the mysql process uses? I any ideas on how to solve this?

I use: Windows 2003 Server, plesk 7.5.6 (windows).

Thanks in Advance