Computer randomly alt-tabs; small terminal window flashes on the screen for a second then goes away...how do I fix this?

This happens even during gaming, alt-tabbing me 2-3 times a game o the desktop, where a small black screen resembling the terminal opens and closes extremely quickly. Happens during casual browsing too. Very frustrating; I just ran a malware scan and nothing showed up. Is there a way I can find the program that is responsible?