Hi Alex, I came across this article on another Vista help forum. It involves rebuilding or resetting your Vista icon cache. Here are the steps and direct link to the article...
Icon Cache - Rebuild - Vista Forums
METHOD ONE: Rebuild the Icon Cache
NOTE: This will delete the icon cache so Vista will wipe out all icons in the cache and reload the icons into the cache for the files as you run across them again.

1. Unhide the system files.
NOTE: Dot Show hidden files and folders. For how, see OPTION TWO here: How to Hide or Show Hidden Files and Folders in Vista
2. Open a Windows Explorer window.
3. Go to C:\Users\(User Name)\AppData\Local (See screenhot below)
4. Right click on IconCache.db and click Delete.
5. Click Yes to confirm the deletion. (See screenshot below)
NOTE: This deletes the file to the Recycle Bin. It is safe to empty the Recycle Bin when finished.
6. Close the window.
7. Empty the Recycle Bin.
8. Restart the computer.
9. When you go back, you will notice the Size of the IconCache.db file is smaller, and the Date Modified is now the current date. (See screenshot below)
NOTE: If for some reason IconCache.db is not there or the size has not changed much, then just restart the computer again. You may need to restart a couple of times in some cases.
10. The icon cache has been rebuilt.
METHOD TWO:Reset the Icon Cache
NOTE: This method is not as thorough as METHOD ONE and is good for minor quirks with the icons only. It will only reset the icon cache instead of deleting it and having Vista completely rebuild it.
1. Right click on a empty area of the desktop and click
Personalize.
2. Click on
Display Properties link. (See screenshot below)
3. Under
Colors, select
Medium (16-bit) and click
Apply. (See screenshot below)
NOTE: If you already have Medium (16-bit) selected, then select Highest (32-bit) instead. Sometimes you will need to do a restart first, then proceed to step 4. Try both ways.
A) Click Yes to confirm the new settings.
4. Now, select
Highest (32-bit) and click
OK.
NOTE: If you already have Highest (32-bit)selected, then select Medium (16-bit)instead.
A) Click Yes to confirm the new settings.