Had this on a Win 7 Pro desktop PC in an SBS 2011 network. Couldn't print from Outlook or Excel reliably. Then spotted Devices and Printers appearing to hang.
Starting BlueTooth and disabling AV made no difference. Cleared temp files and ran chkdsk, no luck. Same problem when logging in as a different user with admin rights.
Finally tracked it down to corrupt System Restore. In Control Panel > System > System Protection there were two entries for C: drive, one listed as off and one listed as missing. Click Configure for the missing one and turn it off. Then click Configure for the remaining C: drive and turn System Restore back on, allocate 5% disk space (or similar).
Did a reboot to be sure and the Devices and Printers was working ok again.
Some more info at TechArena about corrupt system restore and error 0x8007007b