"euro sign virus", have you experienced it?

My kids usually love to play online games... after exiting from the game websites and it was my turn to do some typing, I noticed that everytime I key-in the letter 'e' or 'E' it was automatically changed to the euro symbol... any ideas? When I ran either Avira, Norman Malware or SuperAntiSpyware, it detects nothing but this put everything to normal again. Thanks.