  We address the cause of the unusual muon spin relaxation (muSR) results on
molecular nanomagnets (MNMs). Through measurements on protonated and deuterated
samples of the MNMs Cr7Mn (S=1) and Cr8 (S=0), we show that the muon spin for
$S \neq 0$ MNMs is relaxed via dynamic fluctuations of the electronic spins. A
freezing out of dynamic processes occurs on cooling and at low temperatures the
muon spins are relaxed by the electronic spins which themselves are dephased by
incoherent nuclear field fluctuations.We observe a transition to a state of
static magnetic order of the MNM electronic spins in Cr7Mn below 2 K.
