If you see a blank screen: Your Flash is not installed properly. Check your Flash installation at this page: Test Flash installation. You can also try using another browser or another computer.
That your Flash plug-in is the latest version. Download Flash here
Almost all computer systems work just fine however if you have problems you want to be sure that your browser and Flash is up to date. iOS devices (iPad, iPod Touch, iPhone) do not use Flash and are not affected by these issues.