How can I remove a virus ,on my yahoo messenger?

Thursday, July 29th, 2010 at 8:34 pm

I have recently picked up a virus that is sending random I M s to all of the contacts in my list and now some of those contacts are reporting g that there yahoo messenger is doing the same.I tried removing yahoo messenger from my computer .I waited a day and then reinstalled it.And it still doing the same thing.Any suggestions or solutions would be greatly appreciated.