Depending upon the state where you live, paying it could reset the clock and it won't go off your report until 2014. So do NOT pay it in the hope it will just go away. It won't.
Is it a CA (collection agency) or OC (original creditor)? If it's a CA, send them a DV letter.
"I just pulled my credit report, and I discovered you are reporting I owe you a debt. This is the first I knew of this account, and I request debt validation in accordance with FDCPA."
Send it CMRRR (certified mail return receipt requested), photocopy your signed letter and save the copy, save the CM receipt, save the RRR green card when it comes back, and save the USPS receipt which also has the CM # on it. Also put a reference number at the top of the letter.
USPS CERTIFIED MAIL xxxx xxxx xxxx xxxx xxxx