I seen this issue before (well I seen this once a week)
you need to rebuild the icon cache database,
here is a fast fix (my knowledge base details)
Rebuilding the Icon Cache Database
1. Close all folder windows that are currently open.
2. Launch Task Manager using the CTRL+SHIFT+ESC key sequence, or by running taskmgr.exe.
3. In the Process tab, right-click on the Explorer.exe process and select End Process.
4. Click the End process button when asked for confirmation.
5. From the File menu of Task Manager, select New Task (Run…)
6. Type CMD.EXE, and click OK
7. In the Command Prompt window, type the commands one by one and press ENTER after each command:
CD /d %userprofile%\AppData\Local
DEL IconCache.db /a
EXIT
8. In Task Manager, click File , select N ew Task (Run…)
9. Type EXPLORER.EXE , and click OK .
Thanks
Andrew