windows detects spyware infection

I am getting a little red circle with a white X in my toolbar. Every few seconds, it pops up a window saying, "Your computer is infected! Windows has detected spyware infection! It is recommended to use special antispyware tools to prevent data loss. Windows will nowdownload and install the most up-to-date antispyware for you. Click here to protect your computer from spyware! "
I've run every conceivable antivirus and spyware killer but it is so very persistent.
How can I get rid of it and, just as a matter of interest, where does it come from?

 

Hibg9280.

Sounds like you could ahve one of the SmithFraud\Zlob infections. Lets get a HijackThis! log file and see what else may be on the system.

Please download HijackThis! SetUp from here. Save the file to your desktop.

Double-click the HijackThis! SetUp icon to begin the installation. Follow the prompts for the default install location of:'C:\Program Files\HijackThis'. Tick the 'Create a desktop' button when the option appears. Select next, then allow HijackThis! to start.

Then press the [Scan] button. You will notice the [Scan] button will turn into a [Save Log] button. Click the [Save Log] button and notepad will open up with the contents of the scan. Right-click in the saved log, and select 'copy'. Then proceed to your original thread, unless otherwise instructed and click the '[Reply]' button and paste the saved contents to be reviewed. Do not make any modifications to the log or perform any 'fixes' until told to do so.

I'll move this post to the proper forum too