Trojan Horse Backdoor.subseven 5m

My AVG grabbed this Trojan and is contained in my virus scan. A little later I ran my virus scan again and it showed Trojan Horse BackDoor 5.M again, but this time, it was in my system volume information.

Last week I my virus scan grabbed some Trojans (4 of them) that had the word NERO in the title. I did have Nero at one time but uninstalled it months and months ago.

What is this Trojan Horse BackDoor? This morning, I did notice that my computer screen for my internet was only 4 inches by 4 inches. It was not like that when I went to bed. I am afraid that someone hacked into my computer.

Also, I have other viruses in my Avg Paid Subscription -- They have been in my AVG since Last August -- but I don't know what to do with them. Should I delete them all?

Thanks for any help at all!
MsMandeville

PS: I did the HijackThis Program and I will see If I can attach properly the log. I have no idea if I did it correctly.