|As I understsand you are facing problem with your system, these are the steps, which may help you out if followed:|
1.) Since your system is slow, try cleaning all your Temporary files and Cookies. There is a wonderful utility in internet "Ccleaner" which is used to free your Temporary files and fix Registry problems. Download it and install it.
2.) Since you are using AVG, I recommend you to Unistall it and Install updated version "Bit Defender"or "Kaspersky" or "Avasrt" Antivirus (Make sure that you're using only one Antivirus in your system)
3.)If you're not able to update automatically from internet, you can update your Anti Virus Manually, by downloading the update file from the respective website in another Machine, transfer to your machine and install it.
4.) Once you Update your Antivirus, Scan entire machine with newly updated Anti-Virus
5.) Download and install good Anti-Malware application;
And as I suggest Download "Malwarebytes Antimalware" from www.filehippo.com. Install it and run it.
6.) Once you are done with it Reboot your machine.
Thank you :-)