Some people have encountered hardware-related problems with BeOS 5 Personal Edition, including invisible mouse pointers, strange error messages on startup, failure to work with supported devices, and even lockup on boot. Most of these problems stem from the fact that booting BeOS from within Windows leaves some hardware in an indefinite state, with hardware IRQs and memory registers thinking they’re still in Windows land.
When you boot BeOS from within Windows, you only get a software reboot, which leaves things in a pre-initialized state. Therefore, most of these problems can be fixed by doing a cold or warm boot, so BeOS can initialize the hardware on its own.
The solution is to either boot BeOS from a boot floppy or by installing BeOS to a real partition and then installing bootman. There are several techniques for installing Personal Edition to a real partition here on the Tip Server.
Allowing your hardware to be initialized from a real boot solves many problems with PE which are not technically Be’s fault.
Note: If you already have an R4.5.x installation, you may find that you get all kinds of weird error messages when booting. This is because the bootloader is trying to boot your old partition and getting confused. To solve this, just hit Spacebar as the boot icons start to appear, and select the „Personal Edition“ boot volume instead.
If you get weird boot errors, make sure you don’t have any antivirus software running — the virus checker may not know what to make of BeOS.

KB (KVBudhu@aol.com) adds:
To boot BeOS from floppy faster, press the Spacebar when the boot icons start to appear. Go to boot options, select boot volume, and select „Personal Edition.“ Navigate back to „Continue Booting“. This achieves the same non-Windows effect as booting all the way from floppy, but uses the bootloader on the hard disk, which is much faster than floppy access.

Be’s Travis Geiselbrecht (geist@be.com) adds:
If you try booting from the boot disk or from DOS, make sure there are no EMS memory managers running.
loadbeos.com has to load the zbeos bootloader, which has to load the kernel above any memory that is managed by any DOS memory managers. Sometimes, depending on the setup, this causes the kernel to be loaded too high, which has a definite limit. Anyhoo, booting off of the disk should solve the problem, like most other BeOS PE boot problems.

Sergei Dolgov (dolgov@ut.ee) adds this information:
Some people have the opposite problem from what’s described above, i.e. they can boot successfully from Windows, but not from floppy (sticks on „drive recognition“ icon when booting from floppy or DOS command prompt). This problem may be solved by disabling UDMA in the BIOS, even though the ALI chipset exists in Be’s hardware compatibility list.
Sergei tested this fix on an ALI5 chipset socket7 motherboard.