Do you have latest version of direct X installed??
When Pogo updates any games, the applets already saved on your puter do NOT update automatically.
If you're using Microsoft's JVM, the applets are saved here: C:\WINDOWS\Downloaded Program Files and it should say "Bridge by Pogo". It can be safely deleted, Pogo will just download an updated one next time you want to play. You might want to delete all the games by Pogo while you're there to get all the updated applets.
If you're using Sun Java: Start Menu > Control Panel > switch to Classic View > double click on Java > under the General Tab in Temporary Internet Files > if you click on "View", you'll see a list of EVERY file saved to your puter. You can select them all here and delete them or click "Close" to go back a screen and click on Settings. You can choose whether or not to allow Java to save any files to your puter, or you can set the amount of space used by it. Clicking 'Delete Files' will delete all the ones you were looking at earlier.