document icons missing pt II

[27 houdini's]

i have have a problem with document icons missing (blank symbol) or generic icons appearing instead of (in my case) a thumbnail of a photoshop document (tiff of or any other format)

How can i solve this problem and avoid it in the future. I guess i have the latest os x because i update regularly.

 

[27 houdini's]

i want to add that os x even replaces the icons with iTunes icons when i run that application at the same time with Photoshop. This happens when switching between programs...