Visual Studio 2010: breakpoint hits on wrong file
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I don't have much hope anyone will be able to answer this, but I'll try anyway:

In Visual Studio 2010, when I click to set a breakpoint in any file, another file opens and the breakpoint gets set to the same line number in that file instead.

To illustrate:

 1. I open foo.cs
 2. I click to add a breakpoint on line 100
 3. VS opens bar.cs and sets a breakpoint on (the wrong) line 100
 4. I spew curses at Microsoft

As always, any help would be appreciated.