Try this.
1. Uninstall everything you have on your computer to do with messenger. Plus!, WLM itself, and etc.
2. Go into control panel> internet options> Content Clear SSL slate.
3. Go to Start>Accsessories>Disk Cleanup. Delete all temp files.
4. Open up task manager(CTRL+ALT+DEL). Click the processes tab. Go through that list and see if you can see anything with msg, or something that might relate to messenger. If you find something, end it.
5. Navigate to Program Files, and delete MsgPlus folder, and Messenger folder(In the Windows Live folder).
6. Donwload and install the latest offical version of WLM
See if that works, if it didnt, do everything above again instead of step 6.
7. Download WLM 9.0 from
Here
If that doesnt work, im not sure what could be wrong, could you send a screen shot of all the processes you have running? And a screenshot of your services(Control Panel>Administrice tools>Services).