I'm not sure exactly what the problem is, but there are a lot of steps in penguinbait's directions, and any one of them (or any combination of them) could be causing the problem.

I just released Maemo Mapper v1.3.4 a few days ago, though, which should make penguinbait's procedure no longer necessary. So try installing v1.3.4 by itself instead of using penguinbait's procedure. You can do this in just one simple step by clicking on this link.

proj and/or flite, if you want them, will have to be installed separately. which can be done from the Application Manager after you install Maemo Mapper (the above .install file will automatically add the right repository). There is an issue with flite that may prevent it from installing, but I recommend installing only Maemo Mapper and seeing if you still get the reboot loop. If it works fine, then you can install proj and/or flite.

EDIT: If the .install file above doesn't work, then just enter the repository information directly:

Web address: http://repository.maemo.org/extras
Distribution: mistral
Components: free non-free

Maemo Mapper is in the "Applications" category.