LG GSA 4120B only burns at 2x after flashing


I am owner of few pieces of LG GSA 4120B…I flashed all the units with new A110 (Auto reset) FW…
All the units were working well…But suddenly, after three complete burns one of the LG GSA stoped writting at more than 2x on any media. I use commercial princo media DVD-R 4x…but before this problem issue LG GSA 4120 wrote at 5.31x on these princo media… now it burns only at 2x.

I have checked all hardware setting DMA Mode,all are in correct position.
I use nero 63130… tried reflashing with all the FW avaliable, no results…Any comment? Any wise solution?

P:S. Few days ago I saw a similar thread here posted by other but could not find it, so sorry for the repet.

Use quality media instead. PRINCO IS CRAP!

Ok got you but it gave godd results with this Princo…and now I am using Princo from the same bundle…!