The include references in the g++ include files contain invalid filenames.
Examples are:
_g_config.h instead of _g_confi.h

Workaround:
Edit all of the include files and shorten longer filenames down to 8 characters.

Edit all include files and shorten filenames of include commands down to 8 chars.

This is only a problem for Windows 95, and can be fixed by disabling
the long file names or renaming the short names.  In the next beta,
LFNs will be disabled by default.