Hello,
Would it be possible for you to export the Risk Logs and upload it to us?
That would provide us the inside of the issue.
As per the description the symptoms looks like as suggested by "mon_raralio" above.
Again, what version of SEP 12.1 are you carrying?
If these files are DWH*.tmp files, then check this Article:
When new virus definitions are in place and the quarantine is being scanned, a DWH file is created and detected by Auto-Protect
http://www.symantec.com/docs/TECH102953
Make sure you are carrying the Latest Version of SEP 11.x / SEP 12.1 on your machine, What are the Symantec Endpoint Protection (SEP) versions released officially?
The quarantine scan on virus definition update can be disabled: Edit Antivirus and Antispyware policy > Windows Settings > Quarantine > General, under "When New Virus Definitions Arrive" choose "Do nothing".
Hope that helps!!