Bad luck. I managed in safe mode to start the network, and ran a sudo update to see if that would work (OK).
None of the commands in the google book would work; apt-get could not find gcc-3.4 for instance. Nor the files that should be present as specified in the Matrox documentation were present in the system . I found on the web a free build install kit supporting linux 2.6 versions. That generated the same autoconf.h file missing error. I installed 'locate' and found autoconf.h alright on the disk. It is clearly not in the right place, but seems to be a small part of the problem.
The Graphics on the main board is AGP, and the board has no PCI-e, so a modification is hardly useful. No alternative for Windows XP, which runs out of the box in low res mode (all I need). It still puzzles me that during the installation of LinuxCNC, the graphics card ran OK. No way to shut down the part that screws it up?
Anyway, thanks for the suggestions.
