Avast 2015.10.0.2208 continuously scans a file

[REDACTED]

Hello
I installed avast 2015, but it slows down my PC. I closed everything and there were still many disk accesses.

I checked with the Task Manager. AvastSvc.exe was continously using the disk.
When I desactivate the File Agent AvastSvc.exe stops using the disk.

Checking the statistics I saw the same file on all lines. I added this file in the exclusions and reactivated the File Agent, and now Avast is ok.

Is not it a general problem on random file name since I found 2 other topics near of mine :
 - "10.0.2088 File Shield obsessed with UltraVNC"  https://forum.avast.com/index.php?topic=159809.0
 - "Avast continuosly scans a file while Skype is running"  https://forum.avast.com/index.php?topic=154727.msg1125013#msg1125013

I tried to start a quick scan and I stopped it after a while. In the satistics I now see on all lines a file from my firefox profile...
Strange !