IT all started soon after i started my work on my pc ..its running windows 7 ultimate sp1

when ever i download any files ...in this case lets take the example of a game 

   ..i downloaded a game named HALO4 . when i started its setup they asked me for destination of folder where to install the game....ok   there was a browse option ....well that is easy...but when ever i click browse the setup gets crushed  and this problem is with all the files in my pc ...not only with game setup     if i want to open a zip file and click on   (open file+)  its crushes and this problem is with all my files plz help sir