Whenever I run an app or open a window, Antivir virus software notifies me that they have found a trojan and asks me if I want to quarantine, delete etc. and whatever I click, the same message comes up the next time I run anything. The file, xxyvtrQn.dll in system32 is the one they say is infected, but when I try to delete it manually, it always says there is a program using it. Can I get some help here?