Scareware is a type of malicious software designed to 'scare' the user into downloading or using some form of program by means of shock tactics. Scareware may employ sound, video and/or images to coerce or convince the user that something is wrong with their computer. Some websites will display pop ups that claim that the user's registry is infected, and will offer to solve the problems. The pop ups are designer to look like a notice from the users computer but they are actually a website.
Scareware Lawsuit
In October 2008 , Microsoft and the Washington attorney general filed a lawsuit against two Texas firms, Branch Software and Alpha Red, producers of the "Registry Cleaner XP" Scareware. The company was accused of sending incessant pop-up messages to consumer's personal computers. The messages user's registry was corrupted and damages and offered a download that would fro the problem for a price of between $20-30.atg: Fright Fight: Washington Attorney General leading battle against scareware with Microsoft (September 29, 2008)