http://forums.microsoft.com/TechNet/ShowPost.aspx?PostID=1286744&SiteID=17

" The same thing happened to me after installing VMware.  By default, VMware disables autorun upon installation due to possible conflicts with some drives. Go to HKEY_LOCAL_MACHINE\System\CurrentControlSET\Services\CDRom, and look for the "Autorun" key.  If its value is set to "0", set it to "1" and reboot.  This fixed my problem; I hope it works for others."