I am having a similar issue but i tried what you all recommended. First I uninstalled all my various java programs and reinstalled the latest versions. I did a malware scan and scanned for issues with microsoft security essentials then i pulled up cmd and typed "java -jar C:\Users\Student\Desktop\Runemate.jar it opened the file as expected I typed in my username and password and got the error "could not connect to the server" Here is a screenshot of my cmd.
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My apologies I made this post just a bit too quick and was able to resolve the issue on my own.
However if somebody else may be having the issue "unrecognized windows sockets error: 10106: create" here is how to fix it. Type "cmd" into your start menu and right click the cmd icon and select run as admin. You then type three words in to cmd "netsh winsock reset" with out the quotations and then restart your computer when prompted to do so and the issue should be fixxed