Apple Music won't work on iMac

I'm using an iMac, few months old, never had any problems with it, downloaded the new version on iTunes the other week and been using Apple Music the 3 month trial for the past 15 days, love it, also not had any problems with it, until today.

I turned on my iMac this morning to listen to some music as I crack on with some work, but iTunes won't let me stream music, it will let me play music I have downloaded or saved as "make playable offline" from the Apple Music service, but won't let me stream or download new music, just keeps coming up with this error code (400).

The only music I am able to stream is the Beats1 radio station, and I've reset my computer twice and signed out and into Apple Music multiple times.

Please if anybody could help that would be great.

(Also Apple Music works on both my iPad and iPhone using the same account, just not on my iMac)