This involves changes to the registry, so back up the registry first.
Scroll down until you find the extension of the file type eg .jpg and highlight it.
In the right panel look for the Perceived Type, which should be image.
If that is missing, right click the highlighted value and select: New - String Value
Type PerceivedType and press Enter.
Right click on PercivedType and select Modify, in the value data type image
If the Content Type is missing, repeat the procedure just typing Content Type in the first case and image/jpg (or whatever).
Close the registry and the problem should be solved
Alternatively you can download a Powertoy to do this job click here