Trojan Horse Dropper Agent GIT virus (need help)

hi i've got a virus called "Trojan Horse Dropper Agent GIT" that my
AVG detected and it says it's healed the files that were infected. But when i restart my computer its there again.

When i turn on the computer and when I'm on the desktop screen, there's a display error saying:

C:\Windows\System32\ssttr.exe
Windows can not access the specified device, path or file.....

Can you help me get rid of the virus please...and one of the files that was infected and healed was an 'avgcc.exe' and now i can't open the avg control center.

Thanks

Sam (need_help)