Un-select and reselect the drive volume you do want.
There may be an "EFI Boot" instead of the name when you hold down Option key on startup
X on startup will default to try to boot from Mac OS X volume.
Mac Pro can have 4 or more internal hard drives some of which could be boot drive - kept 10.6.8 on its own drive for one thing, or have a clone w/ 10.7.3 on one and 10.7.4 on another.
you may need to clone your drive. CCC can clone Lion Recovery partition.