.NET crashes when selecting multiple classes in classview

I've converted a VC++6 project to .NET.
Whenever I select more than x classes (depending on the project, or the classes themselves, I don't know) I'm told that .NET crashed:
An unhandled exception has been caught by the VSW exception filter

AppName: devenv.exe AppVer: 7.0.9466.0 ModName: msenv.dll
ModVer: 7.0.9466.0 Offset: 000e94fb

Another coworker has the same pb, opening the same project.

Has anyone run into this pb ? I can't organize the classes in folders if I have to select them one by one !!! it's very unnerving.

thank for any answer