I have just brought my laptop back in to work, switched on and I have this message when trying to build my project:

Invalid Resx file. Licence file not compatible with machine id. Please retrieve a new licence file or purchase an additional SDK.

This is driving me nuts. I have not done a thing and I have not been able to build my project.

How can this happen when it was working fine over the weekend ?

I realise that this message indicates that a license cannot be found but how do I sort this out ?

Any ideas ?