Get the application Little Snitch.
Plus check the MacWorld article First Look: Trojan Horse warning: What you need to know to see if you have been bitten by the p0rn site trojan.
Also go to System Preferences->Accounts, Your User Name, Login Items and see if anything is launching at startup without your knowledge.
Mac Pro Dual 2.8 Quad (2nd gen), 14G Ram, Two DVD-RW Drives, OS X 10.8.3
2006 Mac Book Pro 2.16 (first Gen) OS X 10.7.4
2TB Time Capsule, 2 TB
32G iPhone 4S Black, iPad (3rd Gen) 32G Black