When I plugged in the pendrive (before the pop-ups problem), I scanned it with avast before opening, avast did not detect anything. When I opened it there was a shortcut file in it and I deleted it. The problems started after I ejected my pendrive.

After running the suggested softwares, I plugged in the pendrive again and scanned it with MCShield. It too didn’t find any malware. But the pop-ups started after using the pendrive. I’m confused. Is it safe to use my pendrive?

I’ve attached the MCShield log.