Could this possibly be
http://support.microsoft.com/default.aspx?scid=kb;EN-US;319991 ?
Hope this helps.

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> I am running an ASP project, and when I debug the application pages, then
> exit the application normally the next time I build the environment has one
> of my support DLLs locked.
> I checked what application had the DLL locked and it was DEVENV.EXE which is
> the IDE any idea how I can stop this from happening? It is a serious PITA to
> have to exit the IDE every time I make a change and test it.