using appletviewer

the title expains it all... i dont know how to work the appletviewer. for some reason, whenever i make an html document for my applets, the page jams and an alert comes up and sais <unknown> is preforming an illegal operation...

sometimes the html document works, sometimes it doesnt. thats why i need to know how to use the appletviewer.

thanks.

ps:if you know why the html document goes on and off, id like to know why...