System Restore did not complete successfully: Unspecified Error (0x80070005)

I recently purchased a new Inspiron 15 (5547, Early 2014), Windows 7.  Within a few days, the speed of operation dropped to glacial speeds.  It would take 10-15 minutes to open programs.

I ran the Dell diagnostics, and found no hardware problems.

I've run virus and malware scans and this has not fixed the problem.  I intended to then restore the system to an earlier install point, but every time I do I get a windows error "System restore did no complete successfully.  Your computer's system files and settings were not changed".  The text of the message indicates I shoud disable my anti-virus software, but when I disable it (MacAfee, live scan and firewall), I get the same message.  I get the same message even if I restore from safe mode, with MacAfee disable.

How can I fix the problem above--The real issue is the incredible slow operation--If I can resolve this without a system restore, that would be great.