This can be caused by a few different issues.
1) Adding new drives to expand your RAID Array
2) Adding new volume group
3) Recently ran filesysem repair
4) System rebooted from a power failure
ERROR: No system volume found! System services can't work without system
From the Console UI
1. CTRL + ALT + X
2. Choose "Select default volume group"
2a. If you have multiple volume groups, please be sure to select the correct volume group.