It's a virus. Agent G is its name. To be sure i know what am saying your folder option as been disabled too. This how to check. Open My documents >tools. You need a very good antivirus. Bitdefender will do it easily but it might end up deleting valuable files too. So i go with Mcafee. Get the latest version with updates.
After you done removing the virus. Run the little utility in this attachment
sorry man that is a sign of virus i would advise that you get AVG its an anti virus,scan your system and when it detects a virus just move it to vault because that is d only way it going to stop.and use an updated AVG. good luck