Java SE (Java Platform, Standard Edition)

jdk failed to create file in destination...

im trying to make my own private server and it just wont work! whenever i try it says jdk failed to create file in destination... and im gettin rlly frustrated...
anyways.. im running windows vista and i need help. im not a computer whiz so try to make it as easy for me to understand and do rofl... i have EVERYTHING done for my private server but this! i really need help. i changed environment variables because i thought the dl worked and it didnt. someone plz help asap