For all the people who have issues with SK not runninf properly, please troubleshoot on your own before coming here. The Gamemasters have enough work on there hands, and we shouldn't give them any more. Here are some recommendations for you to troubleshoot on your own:

Reboot
A lot of the time your computer just needs a break, so just reboot. Don't worry, its time well spent because you wo t lose anything during the 5 Mins it takes to reboot.

Force update
Forcing SK to update gives you a fresh set of jar files for the game to run on. Even if you have never touched the SK code this may help.

Scan for viruses
Go and install antivirus if you don't have one already. Norton works extremely well and I would recommend it. If you cant afford it, avast! Free anticirus 7 should do. Do a full computer scan. It is very possible malware has infected SK and is making it malfunction.

Letme know if you have any other questions/comments/recommendations