This is caused by FakeSMC.kext (or dsmos.kext if you're on Tiger) not loading properly. Get the latest version of FakeSMC (if you're using dsmos.kext, there is a version of FakeSMC for Tiger) and install it in /Extra/Extensions. If it's happening on the DVD, go into the ISO of the boot CD your using and look around for FakeSMC to replace. All in all, the goal is to replace FakeSMC, no matter where it is on your HDD/ISO.
I get stuck at "DSMOS has arrived"!
This is a graphics driver issue. First, try booting with:
If that doesn't fix your problem, boot to single-user mode (-s) and type:
/sbin/mount -uw mkdir ~/bkupgfx cd /System/Library/Extensions
Now, if you have nVidia graphics, type:
mv -R NVD*.kext ~/bkupgfx
If you have AMD/ATi, type:
mv -R ATI*.kext ~/bkupgfx
If you have Intel, type:
mv -R AppleIntelGMA* ~/bkupgfx mv -R AppleIntelHD* ~/bkupgfx mv -R AppleIntelSNB* ~/bkupgfx mv -R AppleIntelIntegratedFramebuffer.kext ~/bkupgfx
Now type exit and you'll be done.