help please backdoor trojan keeps coming back

Download Combofix and save it to your desktop.
http://download.bleepingcomputer.com/sUBs/zh/BetaB/combofix.exe

Note: It is important that it is saved directly to your desktop

Close any open browsers.

Double click on combofix.exe & follow the prompts.
When finished, it shall produce a log for you.

Post the ComboFix.txt in your next reply.

Note:
Do not mouseclick combofix's window whilst it's running. That may cause it to stall

Ok, lets make sure the infection is gone

Download and scan with Sysclean Package.
1. Create a new folder on drive "C:\" ("C:\New Folder") and rename it Sysclean.
2. Place the sysclean.com inside that folder.
3. Then download the latest Virus Pattern Files (lptXXX.zip).
4. Extract the lptXXX.zip pattern file into the same folder you created for sysclean.com.
5. Close all open applications and DISABLE your current anti-virus software. Some anti-virus programs such as Avast will alert you to a virus attack when running sysclean so it's best to disable them first. DO NOT perform a scan yet.
Reboot your computer in "SAFE MODE" using the F8 . To do this restart your computer and after hearing your computer beep once during startup [but before the Windows icon appears] press the F8 key repeatedly. A menu will appear with several options. Use the arrow keys to navigate and select the option to run Windows in "Safe Mode".
7. Open the Sysclean folder and double-click on sysclean.com to run.
8. It will take some time to complete. Be patient and let it clean whatever it finds.
9. Exit when done, reboot normally and re-enable your anti-virus program.

Note: This tool generates a log file (sysclean.log) in the same folder where the scan is completed. When using Sysclean its best to use the Administrator's account or an account with Administrative rights otherwise you will not have the rights to scan some locations resulting in Access is denied log entries.

I have attached a file named Seth69.zip, please Extract/Unzip Seth69.reg to your Desktop. Double-click on Seth69.reg and allow it to be merged into Windows Registry.

Download KILLBOX, extract it to your desktop.

Open killbox.exe.

First

Click on Tools>Delete Temp Files

A box will open with a list of all user profiles.

Check the following boxes at a minimum for each profile by clicking on the drop down and checking the boxes that are enabled. Some will not apply and those boxes will not be available to check. Make sure you do this for all the profiles listed.

Temporary Internet Files
Temp Files
XP Prefetch

If you want to clean your cookies, history, and list of recent files run you may check those boxes as well.

Then,,

Check on the Button titled "Delete Selected Temp Files"

Exit by clicking the Button titled "Exit(Save Settings)"

Once back into the main killbox program.

Check the following boxes:

Delete on Reboot

Highlight all the entries in the quote box below and then Copy them.

C:\WINDOWS\system32\grdupdater.exe
C:\DOCUME~1\ADMINI~1\taskmgr.exe

Click to expand...

Then in killbox click File>>Paste from Clipboard

At this point the "All Files" button should be enabled so you can click it.

Click the "All Files" button.

Then click the Red X ...and for the confirmation message that will appear, you will need to click Yes

A second message will ask to Reboot now? you will need to click Yes to allow the reboot.

Note: Killbox will let you know if a file does not exist.

If you have any issues with this method you can copy and paste the lines one at a time into the killbox top box. Then click the "Single File" button. Then click the Red X ...and for the confirmation message that will appear, you will need to click Yes. A second message will ask to Reboot now? you will need to click No until the last one at which time you click yes to allow the reboot

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What is located in your G:\ Drive????