"The visual Studio component cache is out of date, please restart Visual Studio."

The solution was actually very simple. I closed Atmel studio, and looked for

%USERPROFILE%\AppData\Local\Temp\AtmelStudio_7.0.790

I deleted this whole folder, and when I reopened Atmel Studio, everything worked fine.

Using "disk cleanup" to cleanup temporary files and that did the trick - as I do not have the "amtelstudio" mentioned - so that was not applicable in my case.

Using Windows explorer - click on the C drive, go to properties and the disk cleanup button is on that panel. Run that to clear out temp files and whatever it was that Visual Studio was saying was out of date - so it is removed.

Open Run command (window key + r) type %temp% this will open your temp files folder, delete everything. Restart VS