I've had to clean this phis off a few PC's and no antivirus can detect it. S&D will clean it but it will reappear.
It creates a hidden self-perpetuating exe in the registry.
I thot I'd cleaned it, gave the pc back, 2 days later got a call with the popup.
However, there is one circumstance that you can stop it and others like it in future.
If the popup appears, DO NOT CLICK ANYWHERE in the popup window, not even the little x at top right hand corner. The mouse click will initiate a hidden self-copy exe together with modding the IE host.
Save all you opened files immediately. DO NOT SHUT DOWN with windows BUT by holding the power button on the PC itself. Pressing the reset button on resets the system and on some mobo it does not clear the RAM, where this rogue AV resides. Power off at the wall after the PC power is down. Leave it for 1min.
If the above does not work, your hard disk needs to be physically taken out to another PC to be scan offline by AVast.
There would also be a directory called Antivirus2009 in the program files folder, delete it. You can only delete this offline.
Before taking out the HDD start it in safe mode, run msconfig, in Startup stop any process that have a whole lot of numbers and also any process that do not have any information. EXit and save without restarting. Just shutdown. Take out HDD to scan from another PC.
Depending on how long the malware has reside in the system, there might be side effects to windows because the malware makes adjustments to system dlls. If funny things happens during normal windows ops, then there is only one way out, the dreaded rebuild..