Can you enable the trace loggign as per the screen shot?
You might try temporarily lowering the security your local Intranet zone in IE to see if that's the reason it won't come up. Also uninstall IE Enhanced Security Configuration from Add/Remove Windows Components. Check the certificate options, and try playing with those as well and seeing if it makes a difference.
Control Panel - Java - (General)- Settings -Delete Files -OK
this will delete all the cache..
if you run a proxy server you may need to enter that info into your Sun Java client.
then try to go to http:\\\sepm server:9090