Lately my computer has become really slow, especially when I open Chrome. Strange ads pop up even when I'm not doing anything, and sometimes I hear the fan running at full speed. I've already tried Windows Defender but it doesn't find anything.
If Defender doesn't find anything but your PC is still running super slow with weird ads popping up, you should also check your Chrome extensions 🔍 - a lot of malware hides there and doesn't get detected by standard antivirus software.
Open your extensions menu and delete everything you don't recognize or don't use anymore, then restart the browser and see if things improve. If it keeps happening, then yeah, Malwarebytes might find something that Defender missed, but that "surprise" extension is usually the culprit in these cases 😅
Agreed with what was said, Malwarebytes is a solid choice - I've used it myself when something weird happened to my pc after downloading stuff.
One thing I notice is that the fan going full blast could also mean something is running in the background and eating up resources, so I'd also try checking Task Manager (press Ctrl+Shift+Esc) and see which processes are using the most CPU and RAM - if you see weird stuff like strange names or processes you don't recognize, that's a red flag.
If Malwarebytes doesn't find anything, you could also run a scan with Kaspersky Rescue Disk which is more aggressive, but that takes a bit longer and you have to do it from a USB stick. In my case, before I figured out it was actual malware, I noticed Chrome was slow because it had installed some nasty extension, so check there too - go into extensions and see if there's stuff you didn't put there yourself.
When was the last time you checked what's running in the background in Task Manager, especially in the Processes and Startup sections? Often it's not an actual virus but useless programs that launch at boot and eat up resources - you just need to open Task Manager (Ctrl+Shift+Esc), go to "Startup" and disable everything you don't recognize or don't really need!
That said, if Chrome is the main problem, try resetting it completely: go into settings, head to "Reset settings" and bring them back to default values - often compromised extensions or toolbars hide really well and even a scan won't get rid of them.
I had the same problem with Chrome once and the culprit was actually a fake extension that got in somehow. The tricky thing is that Defender doesn't see it because technically it's not a virus, just malicious stuff that hides among legitimate plugins. First, I'd remove all the extensions you don't actually use, then try downloading Malwarebytes in the free version and run it in Safe Mode with Networking - that catches things Defender misses. If that doesn't find anything either, the fan running at max could just mean you have a bunch of useless programs starting up at boot, so take a look at Task Manager in the Startup tab and disable whatever you don't need.
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