Risk: Low
As highlighted in June's Internet Security News, a nasty piece of ransomware has been circulating. The first UK target was identified at the beginning of June and it's thought that she contracted the virus by clicking on a link on the Internet that said her computer had been infected by an unknown virus.
The Archiveus virus password-protects all files found on My Computer and the password is only provided if a victim buys drugs from one of three online pharmacies. Poor programming has enabled security experts to obtain the password and unlock victims' PCs without succumbing to the ransom demands.
Although the virus doesn't seem to be widespread, it should be emphasised that clicking on unfamiliar hyperlinks should be avoided wherever possible.