The problem you are seeing occurs when the Kernel first attempts to locate and check the state of the file system.
Usually by this point it already knows that the partition table exists, but it is now attempting to find the /etc/fstab record to tell it where the root file system is mounted.
If it succeeds in locating the root file system it will temporarily mount it to check it's condition, and then mount it for booting.
You are not getting that far.
A) Linux may be unable to access the HDD
Cabling errors, a dead or shorted drive on one of the IDE connectors, a bad IDE interface, etc. all produce identical errors.
B) Linux may not be able to find the partiton
The kernel initialially loads from a RAMDISK image. This image is loaded into RAM and provides the initialization code you see executing prior to this point. This image gets loaded by the bootloader in one swipe, but it is not the full blow kernel and modules.
Once the root filesystem is found the actual kernel is (usually) loaded and control gets passed to it... however you are not getting that far.
The initrd image may not be seeing the installed kernel.
This can be due to
1) The wrong partiton TYPE selected for the root/boot filesystem
2) LBA or other errors which make the kernel believe that the root system is located somewhere where it is not.
3) HDD failures (see 2 above)
I would try to re-install Mandrake if I were you.
Given the (IMHO) rather meager amount of disk space you are allocating to Mandrake, I'd suggest NOT creating seperate partitons, but rather allocating all the remaining disk space thusly...
512-1gig (do you actually have a GIG of RAM? if so use 1 gig...) to SWAP
/ To the rest of the drive.
No HOME or other partitions.
Finally your machine may have certain problems which do not manifest in Windows, but are there never the less.
You may need to specify certain parameters such as
noapm, nolapic, noapic, nopcmcia
etc... to the kernel PRIOR to startup, before things will function correctly.
On laptop machines this latter problem usually causes the behaviour you've observed, but it also affects some desktop units.