you must be standing to cast a spell
 

ok so im in unrest on red, sitting. ive got maybe 5 death beetles otw that i pulled. im spamming the hotkey for invoke lightning, when all of a sudden my client crashed. i didnt even realize i was getting the message until my system locked up and i have a wall of "you must be standing to cast a spell"

There was no auto-stand on spell casting in classic. However, I believe this was only implemented recently on P99 in the slew of December patches.

This is correct, recently changed, you must manually stand before casting... Also must sit manually before /camp.