Now cannot connect to minecraft server...

I have been forced onto this Minecraft Launcher 2.0.760 and now I cannot log into my minecraft server hosted at clanforge.

I know for a fact it is this launcher because when I log into minecraft on my other computer which has the old launcher it logs into my server fine. All my friends have the old launcher and can connect.

I have attached a screengrab of the error. I am now having to use a 3rd party launcher which is a shame.