The problem is probably related to a device driver on your computer. If you find which one, I'd be happy to know about it.
As for a fix, after you reboot your computer and Plus! does not appear to be here, access the contact list's menu (press alt or click on the menu button on the right in WLM8.5), you should have a Plus! menu sith a single entry about software compatibility. There, you can disable safe mode. Do it and reboot again, this may fix the problem.
Let us know