Richard, there is another way to clear out your flash cache.
Navigate your way to these locations on your PC, then delete the flash folders. If you are uncomfortable about deleting stuff, then rename those flash folders so that the system doesn't recognize them. Then you can go back to using them and their contents later by giving them back their original name.
The aforementioned folders are here...
C : \ Users \ [*** your username ***] \ AppData \ Roaming \ Adobe
C : \ Users \ [*** your username ***] \ AppData \ Roaming \ Macromedia
If you cannot see the AppData folder then you may have to change a setting in the folders options in the control panel. To do that, go to...
Control Panel | Appearance and Personalization | Folder Options
In the Folder Options dialogue box, click the View tab and in the Advanced Settings window, select the Show hidden files, folders and drives radio button, then click OK. That should make the AppData folder appear for you.