computer infected and can't boot time scan. HELP!

[roosterwes]

Something has taken over Avast and my computer. Everything (Avast Internet Security)is set to run and firewall.  Well, all computers in my house, which had Avast. I can't run a boot time scan because there is some red box that disables the keys, and the malicious entity causes my boxes checked to uncheck. It is all over the computers. I sent an email already to the technical department. Can someone help me out?
Thank You in advance. :'(

[essexboy]

Hi lets try this first, if it fails go to Plan B

 Note: If using Firefox right-click on any download links and choose Save As

Please download OTH to your desktop
Please download OTL  to your desktop
Please download the attached file Scan.txt to your desktop

Double click the OTH file to run it and click Kill All Processes, your desktop will go blank.



Then select Start OTL. OTL will now run

• Double-click on the Custom Scans box and a message box will popup asking if you want to load a custom scan from a file
  Select Scan.txt that you downloaded
  
  
• Click the Quick Scan button. Do not change any settings unless otherwise told to do so. The scan wont take long.
  
  • When the scan completes, it will open two notepad windows. OTL.Txt and Extras.Txt. These are saved in the same location as OTL.
    
• Click the Internet Explorer button, post these logs in your Virus Removal topic.
  

Plan B

Download Rkill from here : there are several flavours to choose from, if one does not work then try the next

* rkill.com
* rkill.scr
* rkill.pif


Once it is downloaded, double-click on rkill in order to automatically attempt to stop any processes associated with Security Central and other Rogue programs. Please be patient while the program looks for various malware programs and ends them. When it has finished, the black window will automatically close and you can continue with the next step. If you get a message that rkill is an infection, do not be concerned. This message is just a fake warning given by Security Central when it terminates programs that may potentially remove it. If you run into these infections warnings that close Rkill, a trick is to leave the warning on the screen and then run Rkill again. By not closing the warning, this typically will allow you to bypass the malware trying to protect itself so that rkill can terminate Security Central . So, please try running Rkill until malware is no longer running. You will then be able to proceed with the rest of my instructions.

Do not reboot your computer after running rkill as the malware programs will start again.

Then run OTL as above