This has popped up for me from time to time as I've switched between different versions of Qt (debug/release/static/dll) on Windows 7 and through recent upgrades. I'm getting it now (and don't remember what I did for it in the past, beyond that it required a lot of fiddling around). Preceding this error message, qmake does this:

WARNING: Unable to generate output for: C:/Users/matt/qwtplot3d-0.2.7/qwtplot3d/examples/simpleplot//Makefile.Debug [TEMPLATE vcapp]

I found another thread, http://www.qtcentre.org/threads/3579..._0XE587C205.MK, that addresses a problem like this for Symbian, but I don't feel like it should be necessary to move files around to solve this. If someone could explain this to me that would be great.

Matt