Delete some data from it and if still the problem persists then there must a virus problem in it.......
this sometime happens with folder with lots of images, songs and vids and if there's any app installed on the pc which wants to auto tag them - I had a large folder with lots of pics and opening that would take a long time as acdsee was trying read the tga/exif info everytime I open that folder - after uninstalling acdsee the issue is gone for now and I'm using faststone max view as an alternative imageviewer app.