Over the past week, I've experienced weird behaviors on my computer. They're not major issues, but Avast blocked a virus infection around the same time so I am not sure whether these strange events are associated with the virus intrusion.
1. I could not access certain websites such as gmail, Facebook when some websites such as Youtube open with no problems. It said "This webpage is not available" or along those lines on Chrome, Firefox, and IE. The solution: Reinstall Avast. This happened twice and reinstalling Avast solved the problem.
2. Occasionally, there is a little fragment from my Comodo Firewall's interface on my screen. It is a small rectangle containing the C from Comodo with the grey background that you normally see at the upper left corner when you open up Comodo's interface. This fragment appears on the bottom right corner of my screen above the taskbar and it overlaps everything. I reinstalled Comodo but it still happens from time to time.
3. I can't preview screensavers. Once I click preview, it flashes back to Screen Saver Setting when I didn't even move the mouse.
I've done full scans with Avast, Malwarebytes, and ESET. All said no infections.
OS: Windows 8.1
Any help is appreciated. Thank you very much.