My screen goes to background

[chalindra]

Hi.
I'm in need of some help. My computer does this thing where it stops working, showing 0% use of CPU, and the screen goes to background. And when I say background I mean there is no 'startline' at the bottom of the screen, and all the shortcuts saved to my background is gone.
   The weirdest thing is perhaps that I can have a program like Internet up and running, and even change websites while my computer is like this. But I have no possibility of turning off the computer normally, I have to cut the power.
   I have a Dell Inspiron 6000, and Windows XP. A few weeks ago I had some Trojan horses on my computer, and some system files where affected. There was some trouble with one of them, and a system file may have been deleted. But when I ran a test on my harddisk the computer notified me there was no problems with the system. Oh, and shortly after I was notified a Microsoft program (can't remember the name) needed to be shut down.
   I'm afraid I don't really know what's wrong with my computer or how to fix it. Any help would be greatly appreciated.

[Computer Hope Admin]

Make sure it's not simply that your taskbar containing your start button is not getting hidden by pressing CTRL and ESC on the keyboard at the same time. If done properly this should bring up the start button. If this does work. it's likely your bar is hidden.

If this doesn't work try pressing CTRL + ALT + DEL at the same time and see if any program is in "Not Responding" state and not in the Running state.

Finally, has this issue started occurring recently or is this something that has been ongoing. If something recently, have you installed or changed anything with your computer recently?

[Broni]

A few weeks ago I had some Trojan horses on my computer

and what happened with those trojans?

when I ran a test on my harddisk

what test was it?

[chalindra]

Firstly, to Computer Hope Admin. I tried CTRL/ESC, but nothing happened. And no programs were showing as "Not Responding". I have checked this earlier, also, so I don't think it has anything to do with the programs.
   This started to occur a few weeks back, about two weeks, I think. But now my computer goes to background two or three times a day. I haven't changed anything with my computer recently, no. That why this doesn't really make any sense to me.

To Broni.
The Trojans were deleted after I healed the files that were affected. I had to turn off System Restore temporarily, and delete all Temporary Internet Files. But in the end my computer came out virus-free (thanks to AVG and Ad-Aware) and System Restore is now up and running again.
   The test I ran on my harddisk was a Scandisk test for Windows XP found here: http://www.computerhope.com/software/scandisk.htm

[Broni]

I have to cut the power

Surely, you don't want to do this too many more times, because it's gonna damage your computer.

Even with trojans apparently removed, we better check, if your computer is clean...

1. Run free ESET Online Scanner at: http://www.eset.com/onlinescan/
Note: This Scanner is for Internet Explorer Only
   1.  You will notice that the "Start" button is grayed out. Place a check mark at "Yes, I accept the Terms of use". The "Start" button will become visible. Click on it.
   2. If it wants to install an ActiveX component allow it
   3. You will be asked to install an ActiveX, click the "Install" button (Note: If you have a Firewall install you may have to approve the installation)
   4. Once ActiveX control is installed click on the "Start" button to initialize the scanner
   5. After initialization is complete uncheck\untick "Remove found threats"
   6. Check\tick "Scan unwanted applications"
   7. Click the "Scan" button
   8. Once the scan is done, you will find a log in C:\Program Files\esetonlinescanner\log.txt
Post ESET's log.

2. Download SUPERAntiSpyware Free for Home Users:
http://www.superantispyware.com/

Print these instructions out.

    * Double-click SUPERAntiSpyware.exe and use the default settings for installation.
    * An icon will be created on your desktop. Double-click that icon to launch the program.
    * If asked to update the program definitions, click "Yes". If not, update the definitions before scanning by selecting "Check for Updates". (If you encounter any problems while downloading the updates, manually download and unzip them from here: http://www.superantispyware.com/definitions.html.)
    * Close SUPERAntiSpyware.

Restart computer in Safe Mode.
To enter Safe Mode, restart computer, and keep tapping F8 key, until menu appears; pick Safe Mode; you'll see "Safe Mode" in all four corners of your screen

    * Open SUPERAntiSpyware.
    * Under "Configuration and Preferences", click the Preferences button.
    * Click the Scanning Control tab.
    * Under Scanner Options make sure the following are checked (leave all others unchecked):
          o Close browsers before scanning.
          o Scan for tracking cookies.
          o Terminate memory threats before quarantining.
    * Click the "Close" button to leave the control center screen.
    * Back on the main screen, under "Scan for Harmful Software" click Scan your computer.
    * On the left, make sure you check C:\Fixed Drive.
    * On the right, under "Complete Scan", choose Perform Complete Scan.
    * Click "Next" to start the scan. Please be patient while it scans your computer.
    * After the scan is complete, a Scan Summary box will appear with potentially harmful items that were detected. Click "OK".
    * Make sure everything has a checkmark next to it and click "Next".
    * A notification will appear that "Quarantine and Removal is Complete". Click "OK" and then click the "Finish" button to return to the main menu.
    * If asked if you want to reboot, click "Yes".
    * To retrieve the removal information after reboot, launch SUPERAntispyware again.
          o Click Preferences, then click the Statistics/Logs tab.
          o Under Scanner Logs, double-click SUPERAntiSpyware Scan Log.
          o If there are several logs, click the current dated log and press View log. A text file will open in your default text editor.
          o Please copy and paste the Scan Log results in your next reply with a new HijackThis log.
    * Click Close to exit the program.
Post SUPERAntiSpyware log.

3. Download HijackThis:
http://www.snapfiles.com/get/hijackthis.html
Post HijackThis log.

[chalindra]

You know what, I got the same message again. The program my computer shuts off is LSA Shell, and this is a typical symptom of having the Sasser worm (according to http://ask-leo.com/what_is_lsa_shell_and_why_is_it_an_export_version.html). Funny to say it, but I hope that's whats wrong with my computer, so that when I get rid of it everything will be back to normal.

[Broni]

The choice is yours.