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This message informs you that you have to send an SMS message to a paid service to proceed using your PC. The service will send back a code, which you can then use to unblock your PC.

This malicious type of malware called Trj/SMSlock.A, is being spread as a ‘videocodec’. Victims download a video file, and try to play it. They notice that it is not playing. The media player shows up a message informing the user that they need a codec file in order to play this type of video file. An unsuspecting user will download the codec without thinking it could be malware, and Trj/SMSlock.A happily enters your computer.

The concept of this malicious hijacking malware is not new. Viruses that encrypt e-mail messages in your inbox or important documents found on your computer have been appearing in the wild earlier. After encrypting your files, it asks for money in order to be able to access your files again.

According to experts, this kind of Russian hijacking software is made by amateurs, as it is quite easy to bypass. There are free programs around that generate the SMS codes that you would otherwise have to pay for. Also, the malware is getting blocked by popular anti-virus programs, so i recommend you to configure your anti-virus properly so it updates its virus database automatically every day.