If you happen to have the rogue installer, you can submit it to threatexpert site and get it analyzed. That will help you to get the precise information about the virus.  

If you happen to have access to the rogue/virus installer, you can submit it to threatexpert site and get it analyzed. That will help you to get the precise information about the virus.   

Trying system restore

 If you know the duration since your computer is infected, you can try to restore your computer at a prior date, that will work like a miracle in removing the infection

• Using system restore in windows XP
  •          Using system restore in windows Vista

Using free removal tools

• Special tools to remove a single virus or a family of virus.
• Free Online virus scanners
• Fully functioning antivirus/ antispyware

•  Free tools for windows XP
  
  
  • Free tools for windows Vista

Removing files manually

The steps to be taken to remove the infected files manually   

Remove Processes from Task Manager

Press Ctrl Shift Esc to open Task Manager. See in the list of the processes for a processe/s named av2009.exe , also look for any similar suspicious names,   select if found and press the End Process button. It will prompt you , say yes, and then close the Task Manager.

Optionally you can use Windows Defender to see the path of a currently running program/ process and its publisher, so as to differentiate malware processes from windows genuine processes.

• How to use Windows Defender in windows XP
  
  
  •         How to use Windows Defender in windows Vista

 Removing a Program from windows startup

The system configuration can be started in xp and in vista by typing msconfig in the run box/ start menu search box. In xp by clicking on Start > run . The windows startup is reversible, therefore you can check / uncheck any entry from windows startup any number of times.

After the system configuration utility window is open, Click on the Startup tab, that will list all the programs that are scheduled to start when you turn your computer On. Expand the middle column using your mouse pointer so that you can see the path of the program on the hard disk, that will give you a clear idea, what program that is. Locate and uncheck the entries if  found
"AV09" "AV 2009" or "Antivirus 2009" (look for any other suspicious names) Uncheck the boxe in front of these entries.  This step is very important. The further cleaning depends on cleaning this list. Press Apply , Press Close/Ok ,Stay in the system configuration utility for the next step.

 View Hidden Files

Before you could delete Antivirus 2009 and its associated files you need to search for them, and before doing that you need to enable to view hidden files and folders

•  How to Enable to View Hidden Files and Folders in Windows XP
  •            How to Enable to View Hidden Files and Folders in Windows Vista

Delete files

After restarting the computer, use the windows search utility to search for "Antivirus 2009" "AV 2009" "AV09". This search will find all its folders on the hard disk , delete the folders from the hard disk. Delete its all instances.

Run CCleaner

Even  If you manage to find and delete Antivirus 2009 and its associated files , there will be remaining entries in the windows regitry. If you run a free temp files/registry cleaner called CCleaner, that will automatically clean the registry as well as the temp folder . Click here to read more

Edit Registry

if you are comfortable in editing the registrty manually using the regedit command.

• How to edit registry in windows XP
  •           How to edit registry in windows Vista

These registry entries may be found on an infected computer. Delete them if found.      

HKEY_Local_Machine\Software\Microsoft\Shared Tools\MSConfig\Startupreg\
HKey_Current_User\Software\60146510364805293122982800588910\

(All the keys under this path were found to be created  by antivirus2009. The names were like
AutoUpdate_1, AutoUpdate_2, AutoUpdate_3, AutoUpdate_4, 80d9aadb etc...)

More Problems

If you are unable to open Task Manager, registry editor, system restore, Folder Options etc

If the virus has disabled them. There are free tools and techniques to solve this problem.  They are listed here.

Tools for Windows XP

Tools for Windows Vista

Using the system file checker

If the windows is not functioning normally, you need to make sure if the genuine windows system files are not altered by the virus, you can use the system file checker utility to find it out and in case if they are altered then to repair them. See the appropriate link for your version of windows.

•  How to run System File checker utility in windows XP
  •          How to run System File checker utility in windows Vista

Unable to access security related sites

Using Firewall 

Check your firewall for any suspicious communication from your computer to the internet and block it using firewall.