W32.Nimda.J@mm is both a real threat and a false alarm. There is a real computer worm named W32.Nimda.J@mm which is capable of interrupting functions of security tools. However, the infection is very rare.

W32.Nimda.J@mm is usually detected by rogue security programs. If your anti-virus or anti-spyware reports Nimda.J@mm worm and urges to buy something for deleting the threat, you should really check reputation of your security tools. Fake anti-viruses supposedly detect infections in order to scare people into paying money for fraudulent deals. W32.Nimda.J@mm is reported by VirusDoctor. If the worm is detected by real spyware remover, use the manual removal below.

Delete Virus Doctor to remove W32.Nimda.J@mm pop-ups.

Source: http://www.spywarevoid.com/remove-w32nimdajmm-pop-ups-w32nimdajmm-removal.html