maybe your cdrom-drive is defect /lens is dirty. otherwise, there is a minor possibility that your machine has some hardware that has absolutely no compatibility with linux, and i don't mean the cpu, cause that wouldn't be the problem.
try using knoppix noagp nousb etc, so skip hardware detection..
as for MK10, the only way you can get cd 4 is by ordering the version from Mandrake if i'm correct.. i have got me a copy of MK10 too, but i have the same issue, but you can still install it without the use of the 4th cd..

if all else fails, try another distro again, like slackware 10 or so, i must say i find slackware 9.1/10 the most easiest distro's to install.