My PC briefly acted on its own—what quick fixes can I try?

If you’re concerned about malware, you might want to use anti-malware tools, but just a heads up—many remote access programs that hackers use can be legit software that slips right past those tools. I’d advise checking on any recent installations that you don’t recognize.

I really doubt it’s a real hijacking if it’s happened sporadically. Usually, if someone hacked your PC, they wouldn't just toy around like that. But to check for issues, running Windows Defender could help spot any problems, although it might not catch everything.

It's likely just an issue with your mouse rather than a serious hijacking. I’ve had similar experiences when my mouse sensor gets dirty. Try cleaning the mouse sensor, and if you're using a touchpad, give it a clean with a damp cloth followed by a dry one to see if that helps.

While it’s rare that someone would hijack your mouse to go to eBay, if you’re feeling paranoid, I recommend just doing a quick scan with Malwarebytes or the Microsoft malicious software removal tool. However, the most reliable solution to ensure everything is clear is a complete wipe and reinstall of Windows. If you have programs that are hard to reinstall, like ones that require your college's Wi-Fi, I’d suggest checking in with your college’s IT department to see what they recommend.