Why did my Window Layout changed in VS2010 from one day to an other?

I have been using Visual Studio 2010 SP1 for C++ in the default setting where the Solutio开发者_Python百科n Explorer and all the other tabs are on the left side. I got used to it.

Now today, I start Visual Studio and Solution Explorer, Team Explorer, Class View moved to the right side of the screen, while Server Explorer and Toolbox appear on the left, in a vertical auto-hiding tab. Also, the Output window is now hidden, as well as the other windows at the bottom of the screen.

I tried "Reset Window Layout" in the Window menu, but nothing changes. It seems that this is now the default layout.

How can I get my old default layout back?

When I clicked "Start debugging" for an aplication waiting for user input, while debugging, the good old, original layout appears. But when I finish debugging, the crazy new UI appears again.

What made this new interface appear, and how can I get rid of it for good?

possible idea: I changed monitor from 1600x1200 to 1680x1050 a few days ago. But it worked OK in the first few days. Also, changing resoltion doesn't have any effect now.

Also: If I want to start with a 100% clean VS2010, what are the user registry keys as well as user folders that I need to delete?

OK, here is what I had to do to reset everything to default settings:

Tools \ Import and Export settings \ Reset all settings