seize up
To stop functioning; to come to a halt.
To stiffen or become tight and difficult to move.
To stop working suddenly, and become impossible to start again.
seize upon
To grasp or take hold of (an object) suddenly, forcibly, or tightly.
To take up, embrace, enact, or turn eagerly to (a plan, idea, ideology, cause, practice, method, etc.); to grasp, understand, and accept quickly; to adopt wholeheartedly or vigorously.
To take possession of or claim (an idea, person, event, etc.) as one's own; to assimilate, absorb, annex, co-opt.