I tried to compile a project with Visual Studio 6 SP6 and got the following:
usbcore.h(18) : fatal error C1001: INTERNAL COMPILER ERROR
(compiler file 'msc1.cpp', line 1794)
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18: #include "usbiface.h"
I figured out what caused that error. One of the include paths (passed to a compiler with the /I switch) had a trailing backslash.
The compiler cmdline is:
CPP /nologo /MT /W3 /GX /Zi /Od /I "$(ZLIB_PATH)" /I "..\headers"
ZLIB_PATH had a trailing backshlash. Removing that backslash solved the problem.