If already have BeOS R4.5.x installed on a real partition, and then install BeOS 5 Personal Edition from within Windows, and boot as usual from bootman, you may find that the boot loader gets confused. You may see weird error messages from the media_server, the Deskbar going crazy, and more.
To circumvent this, hold down Spacebar as the boot icons begin to appear and select „boot volume,“ „Personal Edition,“ and „Continue booting.“
The long-term fix is to use the Installer app to upgrade your 4.5.x installation to BeOS 5, then uninstall Personal Edition from within Windows.