This one seems to still be doing the rounds.
Basically, and email pretending to be from American Airlines arrives telling you about either a refund, or a new ticket you have purchased.
If you click on the link, your PC will immediately be infected by a Trojan that is very difficult to remove.
So the best bet is to not be suckered in by curiosity!
There's a link here that we've not tested, but may help. Failing that, honestly, the best course of action after an infection is to wipe clean your hard drive, re-formatting, and do a fresh re-install of Windows.
However, you will lose ALL your data, so you must have had a good backup before doing this.
THREE RULES TO ALWAYS FOLLOW:
Backup all the data you wouldn't want to lose (documents, photos, music, videos etc)
Run a good anti-virus
NEVER click links in emails or social network sites
Good luck!