If you want to know whether or not your machine is sick, you first need to understand the symptoms. Ransomware authors want to make it clear that you have a malware infection. If your screen is loaded with pop-ups, youre looking at an adware infection. Your computer could very well be mining cryptocurrencies without your knowledge. Your Internet is sluggish, your programs are taking forever to load, and your cursor is dragging 20 seconds behind your mouse. You might have tried to open too many programs at once.”]
Source: https://blog.malwarebytes.com/101/2016/05/how-to-tell-if-youre-infected-with-malware/