Hi,
I was running 3.7 firmware on my sansa clip+ and experienced sometimes freezing device during playback so I decided upgrade.
Booting 3.9 firmware, but only asterisk appears after restart ... pressing any button make system rebooting ... again just "*" (no any menu).
I tried 3.8.1 ... endless scanning for files ... menu never appears.
Finally 3.7.1 make things works ... not tested long enough to know if occasional freezes disappeared.
(manual installation - linux)
best regards
mira