Try downloading [size=13pt]Spybot Search and Destroy[/size]
. Once it's set up, run "Check for problems". If there's any spyware or adware, it will pick it up.
I haven't used Avast...I use Avira, which is also free. But these will only protect you from viruses and worms...they won't catch ad/spyware unless you have the premium version. That's why I use spybot, and I run an update and search once a week, works fine.
If these 2 files continue to appear, try to quarantine them if they're not required system files. Good luck.