Problem with DL burning NEC 3520a

Hi,

I burned yesterday my first DL DVD. Media is Verbatim 2.4x certified (MKM 001). I used Nero 7.0.1.4 as burning software . Nero let me to burn this DVD at 4x so I tried to do so. After some time (10-20 seconds) Nero returned error :

17:45:15 #22 SPTI -1106 File SCSIPassThrough.cpp, Line 323
G: CdRom1: SCSIStatus(x02) WinError(0) NeroError(-1106)
Sense Key: 0x03 (KEY_MEDIUM_ERROR)
Sense Code: 0x73
Sense Qual: 0x03
CDB Data: 0xBF 00 00 00 00 00 00 20 00 0C 00 00
Sense Area: 0x70 00 03 00 00 00 00 0A 00 00 00 00 73 03
Buffer x033dee00: Len xc
0x00 0A 00 00 00 00 00 00 00 1F 89 20

17:45:15 #23 Text 0 File DVDPlusDualLayer.cpp, Line 639
L0 Data Zone Capacity not set.
Max LBA L0 2086911 (1FD7FFh, 4075MB), next writable address 0 (0h, 0MB)
17:45:15 #24 CDR -1106 File ThreadedTransferInterface.cpp, Line 1799
Power calibration error
G: _NEC DVD_RW ND-3520AW
17:45:15 #25 TRANSFER -27 File ThreadedTransferInterface.cpp, Line 1799
Could not perform start of Disc-at-once
17:45:16 #26 Phase 38 File dlgbrnst.cpp, Line 1725
Burn process failed at 4x (5.540 KB/s)

After that I tried to burn same DVD at 2.4x and proces was started and succesfully finished. But, I see in the second session log file this lines (2x) :

18:04:13 #27 SPTI -1066 File SCSIPassThrough.cpp, Line 323
G: CdRom1: SCSIStatus(x02) WinError(0) NeroError(-1066)
Sense Key: 0x05 (KEY_ILLEGAL_REQUEST)
Sense Code: 0x24
Sense Qual: 0x00
CDB Data: 0xAD 00 00 00 00 00 00 00 08 04 00 00
Sense Area: 0x70 00 05 00 00 00 00 0A 00 00 00 00 24 00 00 C0 00 07
Buffer x0484d600: Len x804

18:46:54 #44 Phase 37 File dlgbrnst.cpp, Line 1725
Burn process completed successfully at 2.4x (3.324 KB/s)

I’m using NEC original 3.06 firmware.

So, my questions are :

1.) Is it not possible to burn this Verbatim DVD at 4x?
2.) Burning at 2.4x gives me 2x KEY_ILLEGAL_REQUEST error in log file (burn process is completed successfully). Why?
3.) I did quallity scan of this DVD (see attachment). In the PI failures graph I see between 4.0 and 5.0, higher error denisty. Why?

Thanks,

zmaj.

Update Nero. Even it is crappy Nero v7, this could help a bit.