Inactive volume at boot time

I've just had a system which had a problem mounting a logical volume. SuSE 9.3 and

I log in and lvscan says the volume is inactive. vgchange -a y and it is active, and mounts first time. In the boot log:

Scanning for LVM volume groups...
Reading all physical volumes. This may take a while... No volume groups found
Activating LVM volume groups...
No volume groups found

Is there any other way of checking why it couldn't find the volumes at boot time? The two physical drives are seen OK just before the LVM start. I guess another reboot will be the acid test, just wondering if there is another diagnostic I can run.

     John Hearns
     Senior HPC Engineer
     Streamline Computing,
     The Innovation Centre, Warwick Technology Park,
     Gallows Hill, Warwick CV34 6UW
     Office: 01926 623130 Mobile: 07841 231235