Ya need to get the database into sufficient shape that it will reboot (power cycle) into v3alpha3 without rebuilding every boot. Once that works, I'd expect v3alpha5 to work as well for you as it does for me/Rob.

Just for kicks, I did the following:
-stop the (alpha 3) player
-rw
-rm the database3 file
-start the alpha3 player
-let it finish building
-stop the alpha3 player
-ro
-reboot
-alpha3 rebuilds the database

I then repeated above, adding 1 step: sync with jemplode between "ro" and "reboot".
-alpha3 sees valid database

-stopped alpha3 player
-rw
-replaced alpha3 with alpha5 player
-ro
-reboot
-alpha5 "rebuilds" database, finds no music

-stop alpha5 player
-rw
-put back alpha3 player
-ro
-reboot

and all is well again (no rebuild, music's there)

So if it works for you and rob (and others), I'm unlucky, or something's different about my player. I'm fidsifted, I have hijack 347, and have ~12000 songs.