Yes it sounds weird, and it is weird. But i am sometimes having brain crashes.

My experience is: Sometimes when i have vivid or lucid dreams, i am having HARD pain bursts inside of my head. Its like your brain lights on fire and electrical shocks TOGETHER!

Symptoms of brain crash:

Blackness, then suddenly CRAPLOADS of dark toned colours
Pain in form of: Electrical shocks and burns

Effects:

Headache
Dream-messup
False awakenings (Especialy when you want to get out of the pain)
Adrenaline rushes (When awake)

Occurs when:
In-dream stress
Fear
Excessive desires to end a dream
Handling waking in a explicit way.

Just like WIndows 98 fatal errors

But now i ask you ladies and gentlemens: Have you experienced this before?