Bug? Git checkout fails with a wrong error message

Hi,

I am using Git alone for my local software project in Visual Studio 2010. I've been on the master branch most of the time. Recently I created a new branch to do a larger refactoring of one of the dialogue windows. I did the following modifications:

* Rename Form1 to Form1a (including all depending files)
* Add new Form1

I checked this change into the branch, say form-refactoring. Interestingly, Git didn't notice that I renamed the file Form1.cs into Form1a.cs and created a brand new, totally different Form1.cs, but instead it noticed a new Form1a.cs file and found a whole lot of differences between the previous and new Form1.cs files. This will of course lead to totally garbaged diffs, but I don't care in this case as long as all files are handled correctly in the end.

Then I switched back to master to do some other small changes. Nothing conflicting. Until now, everything worked fine.

Today, I wanted to switch back to my branch form-refactoring to continue that work. But all I get is the following message:

----- git.exe checkout form-refactoring

Aborting error: The following untracked working tree files would be overwritten by checkout: Form1.Designer.cs Please move or remove them before you can switch branches. -----

What is that supposed to be? The mentioned file is not untracked. Neither in the master branch, nor in the form-refactoring branch. It is part of both branches, but one is not a descendent of the other (because it was recreated on the form-refactoring branch, if that matters). What would happen if I delete it, is it gone for good then? I don't trust Git to bring back the correct file if I delete something now. I did not play with any file at all outside of my mentioned Git operations, so why should I play around with any file to continue using Git operations now? Git broke it, Git's supposed to handle it now!

Here's some other input:

There are no uncommitted changes in my working directory. 'git status' doesn't list anything.

The file in question is not untracked. Right now on the master branch, it has a green checkmark in Explorer (provided by TortoiseGit) and it has a history as well. There are more Form....Designer.cs files that don't cause any trouble.

'git clean -f -d', 'git reset --hard HEAD', 'git stash' do nothing and don't help resolving the issue.

Right now, I cannot continue with my work because I cannot switch branches. Is there an easy solution to this? Is my Git repository broken, all by standard operations?