Maybe something in context menu (right click menu) crash explorer ?
If i read it right, the problem is only with the files.
If you right click on a folder explorer work fine.
Download [URL="http://www.nirsoft.net/utils/shexview.html"][B]from here[/B][/URL][B]ShellexView[/B], and[URL="http://www.nirsoft.net/utils/shell_menu_view.html"][B] from here[/B][/URL][B]shellMenuview[/B]
First run ShellMenu.exe and disable evrything you find suspicious.
Then run the ShellexView and do the same.
To disable an item just select it with your mouse and then click the red button on the uper left corner of the Window.
You may need to disable them all and enable them one at the time, to find what cause the problem.