1. Determine whether you have MyWebSearch Toolbar, Smiley Central, Messenger Plus, Kiwee Toolbar, Info Pen or MacroGaming SweetIM installed in your computer. If you have them installed, uninstall them.
a. In WINDOWS XP, click Start, click Run, type Control Appwiz.cpl in the Open box, and then click on OK to open the Add or Remove Programs item. In WINDOWS VISTA, click Start, type Control Appwiz.cpl on Start Search box and then press on ENTER.
b. In the list of installed programs, search for any third-party toolbars, such as MyWebSearch Toolbar, Smiley Central, Messenger Plus, Kiwee Toolbar, Info Pen or MacroGaming SweetIM and then uninstall the program.
c. Restart the computer.
d. Sign in to Windows Live Messenger.
2. To install the latest version of DirectX, visit the following Web site: http://www.microsoft.com/directx
3. Go to http://www.microsoft.com/protect/computer/spyware/default.mspx to check for spyware. You can also try this URL link http://www.microsoft.com/security/malwareremove/default.mspx.
If the issue persists, it is possible that you have corrupted files associated with Windows Live Messenger. We will do what we call a Clean Install. This is different from the usual uninstall and reinstall process because here, we will completely remove all the components of Windows Live Messenger and install it anew. I know that the steps are lengthy and technical at some points.
For the steps, along with screenshots, please go to http://messenger-support.spaces.live.com/blog/cns!8B3F39C76A8B853F!15345.entry
4. Windows Live Messenger and an earlier version of Adobe Flash are known to have some conflicting issues when Data Execution Prevention is enabled in Windows Vista. Follow these steps to make sure that you have the latest version of Flash on the computer:
a. Visit the following Web site to verify that you are running the latest version of Flash for the operating system:
b. The Web site will detect what version you currently have installed. Scroll down and confirm in the "Current Flash Player versions" table that you are running the latest version of Flash on your computer. If you are running the latest version, skip this step (STEP 4).
c. Uninstall the current version of Flash. For instructions, visit the following Web site:
d. Visit the following Web site to install the latest version of Flash:
e. Restart the computer, and then try to sign in to Windows Live Messenger.
5. If you have the Nvidia Network Access Manager preinstalled on your computer, try to disable it temporarily from the Windows Task Manager.
a. Click Start, click Run, type taskmgr.exe in the Run box and press ENTER or click OK. If you are on WINDOWS VISTA: Click Start then type taskmgr.exe on the Start Search box. Press ENTER.
b. On the Windows Task Manager window, click the Process tab.
c. Under Image Name, locate Nsvcappflt.exe and click the End Process button.
d. Click Yes to confirm.
e. Attempt to sign in to Windows Live Messenger.
If you wish to uninstall the Nvidia Network Access Manager from your computer, please contact your computer manufacturer for further assistance.
6. Perform clean installation of Windows Live Messenger. Please visit the URL appropriate for your Windows Operating System: