This is very weird!
----- s n i p -----
root pegasos:~# pvscan
PV /dev/hdb VG MovieShare lvm2 [74.53 GB / 74.53 GB free]
PV /dev/sdb lvm2 [372.61 GB]
Total: 2 [447.14 GB] / in use: 1 [74.53 GB] / in no VG: 1 [372.61 GB]
root pegasos:~# pvcreate /dev/sda
Physical volume "/dev/sda" successfully created
root pegasos:~# pvscan
PV /dev/hdb VG MovieShare lvm2 [74.53 GB / 74.53 GB free]
PV /dev/sdb lvm2 [372.61 GB]
Total: 2 [447.14 GB] / in use: 1 [74.53 GB] / in no VG: 1 [372.61 GB]
----- s n i p -----
Any ideas?