Ah -- the edit you made on the file formats changes things. Beginning with CS2, Adobe stopped supporting thumbnails of PSDs. However, a number of people figured out that you could change the registry manually to get that functionality back. You may have done that before and had forgotten it. The reinstall put the registry back to the default. Here is one option: http://www.aeonity.com/david/adobe-p...ndows-explorer
Please note that this site is instructing you to download a file and then import that file into your registry. Verify that you are on the same version of OS and PS. If you're different, just Google something like, "PSD thumbnails Vista CS3"
Good luck - should be a quick fix.