Even bigger problems with My Lite-On LH-20A1P



I have just bought another 100 pack of Taiyo Yuden DVD-R’s (TYG02)
I had a few of the old DVD-R’s left which are TYG03. I was getting scans of a quality score reading around 93 and 95 usually. I was extremely surprised to see that after some burns i did (With the old and some of the new DVD-R’s i got) i was getting quality scores of 23. But the thing is i’d scan a particular disc and it would read 23 for the quality score at the front of the scan then i’d scan the same disc again and it would read a quality score of like… 15 at the end of the scan! It seemed to change everytime where the bad parts were. Really weird.
I was wondering if you lot coul;d help me get good burns again and maybe tell me why this is happening and what i should do to fix it.
I just bought this writer and i don’t really want to kep buying writer after writer.
My DVD-R’s are being burned at roughly around 8x and 12x using Nero Burning Rom.
I have not made any changes to nero, so this problem i’m getting is very random.
Here is a pic of the results i got plus the info:

General Information
Firmware: KL0N
Disc: DVD-R (TYG03)
Selected speed: 4 X
PI errors
Maximum: 90
Average: 13.47
Total: 225103
PI failures
Maximum: 21
Average: 1.04
Total: 139411
PO failures: n/a
Jitter: n/a
Scanning Statistics
Elapsed time: 13:37
Number of samples: 116231
Average scanning interval: 1.15 ECC
Glitches removed: 0