I kinda had simmilair thing once, added a drive, made it a physical volume, added to the volume group, made some logical volumes, moved some data (removed an older, slower drive) and put some mount points into fstab.
That really was simple. Everyting worked.
So i gave the box a 'three finger salute'.....maybe i should have done a 'sync' before that:
The uuid from the second disc was not written to the drive, so the volume group was incomplete. Because i was testing some features like striping, a lot was gone
I started over, hope it isnt as bad with you as it was with me and my holiday photos....
PS: you should try 'hirens' disc (sure you can find it), it has a lot of recovery/diagnostic stuff to boot from cd.
Good luck!
PS2: now succesfully using lvm2 with striped volumes, now using ext3 though.