Well I upped to PSU from 300W to 400W and checked a pessed disc (Braveheart) which the Liteon read as a Video DVD. Thought, well it has been fixed.
Then tried the pressed DVD that it wouldn't read yesterday and no joy. The drive, after much searching finally sees the pressed disc as a blank CD. It appears to be some inconsistency between the Liteon and the disc. There were three discs in a set, Home Alone, Home Alone 2 and Home Alone 3 and all three were unable to be read by the Liteon but were able to be read by the Pioneer.
Checking out the disc through the Pioneer with DVDInfoPro it is shown as a pressed DVD-ROM.