Every once in a while my computer loses internet connection for some weird kind of reason. When I go to e.g. 192.168.178.1 it actually shows the correct login page for my modem but it just won't connect to the internet. My laptop and other devices work fine and can connect correctly to the internet.
When I restart my pc I also notice that some USB devices won't work anymore once the operating system shows up (Windows 8.1) and my background wallpaper is no longer positioned to span across two monitors either. Sometimes after serveral minutes the usb devices start responding suddenly again, but this however, takes really long.
Lastly shutting down and restarting makes my pc act kind of strange aswell. When my pc shuts itself down, the monitors lose signal (as used to and should), however my pc keeps running for another 5 to 20 minutes. When restarting, the computer will stay at the Windows 8.1 restarting screen (where it shows the loading ball thing and the text stating "Restarting...") and after it restarts, the motherboard bios screen will be shown and freeze there (cannot enter the bios and won't load operating system).
Does anyone recognize this problem and might be able to help me out?
(Are computer specifications required to answer this question? If so, please let me know in a comment so I can update the question).