Zapping PRAM/NVRAM has only a few uses and this is one of them.
Troubleshooting Mac OS X 10.2.4: Resetting NVRAM for sleep problems
Margin Note: Why are three chimes recommended for a PRAM/NVRAM reset?
More fixes for this surprisingly problematic update.
The OS X boot arguments are useful for troubleshooting problems with system startup and how the system behaves when running.
If you have a Bluetooth keyboard, OS X may ignore keystrokes at startup for booting into Safe mode and other optional boot environments.
A quick PRAM reset or settings change may help a stubborn MacBook that refuses to enter clamshell mode.
XLR8 updates Emergency Disk to remedy "firmware fix" problem
Often when troubleshooting problems in OS X, booting to Safe Mode is one step to minimize the boot environment. Here are some options for how to do this.
Apple supplies various alternate boot modes for OS X, but sometimes systems get stuck in them.