I have the most recent version of Yahoo messenger and now when I click on certain things (ex. my online status) then it shuts it yahoo messenger down immediately. Has anyone else had this problem? It didn't start happening until I redownloaded the Microsoft Anti-Virus sofware and "quarantined" the PowerReg program....(or at least I think that is what it is called.)

I'm sorry, I don't have an answer to your specific problem. I would suggest trying software that includes the Yahoo client, like Trillian.

Also, Microsoft Antivirus? I wasn't aware of such a program...

Maybe you should check your event logs and see if any program errors were reported.

Also check to see if you have any spyware installed. A spyware blocker might be killing the yahoo client.