Wondering Problem with Sony DVD RW DW-Q120A

hey there,
i recenly bought say almost a 20days or so back a SONY DVD RW DW-Q120A dvd writer, everything is fine but 2day in the noon while i was burning some cds (video cds) i found a prob.

I used sony 700mb standard cd for burning. I had 16cds and out of tht 5 are not getting written using this dvd writer. As in it goes and starts da cd writing but then gives en error like ILLEGAL DISC and also says POWER BURN activated. I’ve completely no idea whtz da matter… Yes this is a OEM dvd burner/writer so is this the problem? like OEM version of this burners have problem in burning some cds??

SOFTWRE USING: NERO and also let me tell u the other SONY cds werked fine facing prob with just the other 5 and other 11 were also da VCDs only. Also after that screwd cd is out and when i try to reburn it, it shows an error while burning in NERO : The Disck is unwritable/not writable.

Please help me

Thanks and regards for the suggestions b4 they arrive.