You didn`t attach an AVG Antispyware log, nor did you let us know the results of the AVG Antirootkit scan. Please do so in your next reply.
You might want to copy and paste these instructions into a notepad file. Then you can have the file open in safe mode, so you can follow the instructions easier.
Boot into safe mode, under your normal user name(NOT THE ADMINISTRATOR ACCOUNT). See how [URL="http://www.bleepingcomputer.com/forums/tutorial61.html"]HERE[/URL].
In Windows Explorer, turn on "Show all files and folders, including hidden and system". See how [URL="http://www.bleepingcomputer.com/forums/tutorial62.html"]HERE[/URL].
Click start/run and type services.msc into the run box and press the enter key.
When the window appears, maximise it. Double click on the following services(if there) and select stop if they are running. Set the startup type to disabled. Click apply/ok for each service you disable.
ms hexidecimal defx (mshexdefx)
Close the services window.
Open your task manager, by holding down the ctrl and alt keys and pressing the delete key.
Click on the processes tab and end process for(if there).
Close task manager.
Run HJT with no other programmes open(except notepad). Click the scan button. Have HJT fix the following, by placing a tick in the little box next to(if there).
O23 - Service: ms hexidecimal defx (mshexdefx) - Unknown owner - C:\WINDOWS\system32\dllcache\ivchost.exe (file missing)
Click on the fix checked button.
Locate and delete the following bold files and/or directories(if there).
Reboot into normal mode and rehide your protected OS files.
Post fresh HJT, AVG Antispyware and Combofix logs as attachments into this thread, only after doing the above.
Also, let me know the results of the AVG Antirootkit scan.