Today while I was playing a game on my PC I heard the Windows alert sound, but when I checked to look there was no alert to be seen. Shortly afterwards my PC was disconnected from the Internet. Chrome said that my device is offline, this usually never happens. My phone could still connect to the internet without any problems though. I checked the recently modified files on my PC and there were changes made to both my LocalService and NetworkService folders around the time I heard the alert sound. Also a few changes in System32.
I ran Avira and Malwarebytes scans and neither found anything. Just last week something similar happened where my PC was connected to an unknown network and was playing windows alert and Skype sounds that were not caused by me. A member of this forum said that it was a malware issue. I have since reset my PC twice, removing all programs and personal files.
My PC is connected to my router via LAN and has no Wi-Fi connectivity. Could there be something wrong with my network?