Hello,
I seem to have a similar problem to this one.
I have a HP Probook 4330s. I recently bought an external WD Mypassport usb HDD and installed MacOsX there (didn't want to mess my internal drive partitions because it's a business laptop).
Before Chameleon, the dreaded EBIOS errors appear for 30 seconds, then Chameleon loads and I can boot into MacOsX normally. I have tried almost everything noted here. Is there something I am missing and could try doing? I have done everything that can be done inside MacOs X (permissions repair, Boot/Kernel cache rebuilt etc. )
Any suggestions? Thanks in advance.