how can i fix this problem?

it sounds like a worm ... they usually duplicate tasks and viruses. Worms won't be found with anti-virus software because they set-up in your registry and evade virus scans.

2 ways to get around it

... put your hard drive in an external case and load windows up on another hard drive .. or find somebody that has an AVG or Avast program on their computer ... from there, scan the hard drive for viruses (while it's in the case). This will allow the drive to be fully scanned because the operating system on the hard drive isn't being used and therefor the registry isn't being used.

or

save your files onto CD .... not programs - just your pictures, music, work files .... reload windows onto the hard drive and re-install office. If you do this ... this time have the anti virus on FIRST before you get the virus.

Then I recommend the following which I'm copying from one of my replies to somebody else :

PROTECTION (without spending a cent)
From here, there are a few things that I can recommend to you that will keep your computer free from problems in the future and the programs will update themselves and you won't need to touch a thing.
1. Go to internet explorer and type in
http://www.mozilla.com/en-US/
download Firefox to your desktop and once it's on your desktop install it. it will ask you to import things from internet explorer - do that ... and then it will ask to import your homepage .... just do that too.Of course, restart the computer after installing it - you'll get used to this! what you have downloaded is a internet browser that is much safer than 'internet explorer' ... so right-click on all the internet explorer icons you see in your startup menu and desktop and delete them so nobody uses internet explorer by accident - the program won't be deleted though, just leave it alone.
Now open Firefox and select 'tools' from the top bar and then 'options' in the window that pops up. There are a few categories ... in 'main' type in your starting page ... I use Google. Under 'tabs' uncheck the two options that warn you .... it's a pain and not needed. In the 'privacy' section the only ones to checkmark are "always clear private data..." and "accept cookies ... " to which you set to "I close Firefox". Under 'Security' uncheck the option to remember passwords.
good. now the browser is almost setup.
Now for the add-ons.... type the following address into your computer:
https://addons.mozilla.org/en-US/firefox/
this is the add on page ... they add gadgets to your website to add further protection and features.
There's a textbox above the little motorcycle on this site .... type each of these in this square to go directly to the add-on so you can download them individually.....
Downthemall
Flashgot
Adblock plus
Fasterfox
PhishTank SiteChecker
Macfox (optional-changes the look of the browser..I use this one)
when you type each one in, you will have a list pop up, just click on the name and then download the file.
Now close Firefox and then open it again ..... some pages will welcome you to these add-ons...just close them.... a grey screen will pop up asking you to subscribe to some lists ... pick the USA list. Now you you have a bulletproof web browser that updates itself automatically and protects you from getting most malware in the first place.

For anti-virus software, I use AVG (just type 'AVG' in the search window to go to the site ...then go to 'downloads' on the website)
I also use their AVG anti-spyware and AVG anti rootkit. These are all free as well and updates every day which makes Norton anti-virus and Mcaffe look useless and a waste of money (not to mention neither of these programs detect even half of what AVG can)
With Firefox and the 3 AVG programs, your computer will be very hard to get viruses onto again.

Jason
January 2008