A common cause of such behaviour in computers (predominantly notebook types) is overheating so a clean out with canned compressed air is a first step, a cleaning guide to help is available from Here,
it is for HP products but the principle is the same.
For now the above is all that I can suggest due to the possibility that this is malware related, this based on the information provided by yourself in that you have no AV protection and spend a lot of time connected to the internet, please refer to the GTG malware redirection information below;
I suspect that you have some malware on your computer causing issues that we are not able to solve through means we can use here in the Tech Forums. I suggest you read the 'Start Here'
topic found here
. With these self-help tools you have a high chance of fixing the problems on your own. If you are still having problems after following Step 3 of the guide, continue with Step 4 and 5 and post in the Malware Forum
. If you are unable to run any programs, Please create a topic stating what you have tried so far and that you are unable to run any programs. Also, Please do NOT
post the logs in this thread.
If you are still having issues after the malware expert gives you a clean bill of health, Please return to THIS
thread and we will pursue other options to help you solve your current problem(s).