[To get dosbox 0.74 to recognize it, it was necessary to mount c.img with size 512,63,64,1023. Otherwise it won't work]
Anyway I'll post all the details regarding my error soon, but so far I've been following robertomo's advice [http://www.vogons.org/viewtopic.php?t=25673&sid=69ba74999e52350df061b76bf9d271fd]:
"Windows 95B and 95C installs OK without any errors if you choose minimal installation, with standard vga and no sound card. You can detect new hardware, update drivers to S3Trio32/64 and PNP monitor and install additional windows components (if you need any) after installation. (if you want IE4.0 too, install IE4.0 before adding all these things)"
All works, appart from installing IE4.0, which gives the aformentioned error
