Windows

You didn't say what type of video card you have installed. Does it have the latest drivers installed? Try moving it into another slot. Also, is the keyboard F5 key the problem? Try swapping out the keyboard with a known good one just to make sure. Can you set the refresh rate for your video? Try different settings if the first two suggestions don't help, just remember what your original setting was as it's probably the default. Good luck.

This same thing happened to me. I tried the video drivers, etc as mentioned above-- To no avail. (not that you shouldn't try that anyway, JIC)
It eventually drove me so nuts that I buckled down and reformatted and did a fresh install from (literally) scratch. That fixed it for me.

In one of your folders, go upto View>Folder Options.

In there choose the View tab and click on Restore Defaults. Then Apply it to all folders by clicking on the "Like Current Folder" button. This will restore all default settings in the folders, which should include automatic refresh. If this does not work, please reject this straight away so I can give you info on other methods,

Hope it works though,

Steve