I've completed an install of Mandrake 9.1 (several times now) on my P4 Celeron 2.0G with 128M ram. I've got a 10G hard drive, and a wireless NIC (Linksys) in it. It installs fine, but whenever it boots, it gets to:

Building Window Manager Sessions [OK]

then locks up. Have to power cycle it to free it up. I've tried booting in normal and failsafe mode, same thing each time.

Any thoughts? I'd really rather run 9.1 than 8.1, which is the last ver I could get to work.

Thanks in advance,

Aad

Hope it will help:
I had the same problem (Mandrake 9.1 hanging on boot at "Building window manager sessions") on my computer.

After a few installations, i figured out that the IP i was affecting to my ethernet card was already in use. That was preventing linux from correctly booting. After fixing this mistake, i managed to boot normally.

I checked the boot sequence and the next step was effectively the activation of network devices.

So i suggest if you're still looking for some ideas for solving your problem
to try changing your network configuration.