This is not related to navigator, but JAVA enhances its security since version 7
update 40: you cannot allow permanently any more an applet, if it's not signed by an
"official" site. Only one shot launching is allowed.
And they say that in next updates, you'll cannot *launch* any more an applet
if not signed by an approved authority.
If you wanna see it, update to 7_u40 and try this: