Hai friends just follow the simple steps Below:
1)Right click on the Google Talk shortcut.
2)click on Properties.
3)Go to Shortcut tab on Google Talk Properties window.
4)On the Target textbox, add in the /nomutex to the end of the line so that it looks like below (or you can simply copy and paste the below syntax and replace the original).
“c:\program files\google\google
talk\googletalk.exe” /nomutex
5)Click on OK.