Open the Registry Editor click on the Start button on your taskbar, then click on Run and type “regedit” and click on OK to start the regedit utility.
Expand HKEY_CURRENT_USERSoftwareMicrosoftWindows CurrentVersionExplorerAdvanced
Modify or create, “EnableBalloonTips” and set the Value to “0″. To restore set the Value to “1″.
or you can download the registry here