Thanks for the replies guys... But to further explain my problem.
The DVD R+ recorded previously in PC and Liteon played and read fine. I could add to multi titles etc on DVD's recorded by the Liteon.
Without changing anything (firmware etc) the R+ DVD's slowly started to have the odd read 'FAIL' where if I opened and closed the tray several times it would pick up and read etc. So it was intermittent with the same R+ discs. Now it is a permanent read issue. It was mentioned about cleaning the drive witha cd cleaner - But ALL the DVD RW+ read everytime without issue, its only the R+ that fail to read.
Could it be a hardware failure?
What makes an RW+ different to read than an R+?
I only updated the System and drive firmware (098) in an attempt to solve this issue, but it did not and did not cause any new problems with playback of my RW+ discs.