I think you'll find that C/System Volume information/_restore{7D90F8FC-7017-4D-3D-B54C-8581A6BA87A4}/RP159/A004 5820.exe is the System Restore folder, so you will need to disable System Restore (Right click My Computer > Properties > System Restore tab) before trying to remove the trojan, or it will keep coming back. If you do that first, try AVG again, but you obviously haven't got adequate protection, otherwise it wouldn't have got in in the first place.