>>Few things to look for: check the Show Errors checkbox when building, and Recompile would also be a good idea. Also, packing the project (Clean up project, as it's called in the menu) might help. Try to remove any project hooks - though it's a shot in the dark, don't see how they may benefit from debugger.
>>
>>Worst case, build a new project from qms.prg and up.
>
>Hmm, I thought you made a better suggestion recently how to get information about which file is the problem while building a project. I guess I didn't use the right search keywords.
>
>UPDATE. And I see it in the same thread.

As you see, that was the case when it didn't work either way - debugger or not. Then the last line in the output window is either the offending piece of code or the previous one. However, in this thread it works with debugger open, so debugout window would probably show everything OK, which doesn't help to trace the offender.