|What software do you normally use to open that type file?|
Click once on the file to highlight it. Then while holding the SHIFT key down, right click on it. The box that opens will have an 'open with' option. Click on that and then see if the ensuing list includes the software you use. If so, click on it and check the box at the bottom that says 'always use this program to open this type of file'. Then click OK.
Real men don't use AntiVirus; they just reformat