Thanks for your answer (and link)...this is what about I was afraid of, reading some posts in this forum...
BTW ImgBurn is Great ! Gonna get some Verbatim discs ASAP ^^
Here's another log file (with no-re-re-try after fail) for the story to be complete :
I 10:11:45 ImgBurn Version 2.5.7.0 started!
I 10:11:45 Microsoft Windows 7 Home Premium x64 Edition (6.1, Build 7601 : Service Pack 1)
I 10:11:45 Total Physical Memory: 3 977 064 KB - Available: 1 372 992 KB
I 10:11:45 Initialising SPTI...
I 10:11:45 Searching for SCSI / ATAPI devices...
I 10:11:47 -> Drive 1 - Info: HL-DT-ST DVDRAM GT32N AS01-10 (E:) (ATAPI)
I 10:11:47 Found 1 DVD±RW/RAM!
I 10:12:33 Operation Started!
I 10:12:33 Source File: G:\Slice\snowleopard_10a432_userdvd.iso
I 10:12:33 Source File Sectors: 3 794 608 (MODE1/2048)
I 10:12:33 Source File Size: 7 771 357 184 bytes
I 10:12:33 Source File Volume Identifier: WindowsSupport
I 10:12:33 Source File Volume Set Identifier:
I 10:12:33 Source File Application Identifier:
I 10:12:33 Source File File System(s): ISO9660; Joliet
I 10:12:33 Destination Device: [0:1:0] HL-DT-ST DVDRAM GT32N AS01 (E:) (ATAPI)
I 10:12:33 Destination Media Type: DVD+R DL (Disc ID: CMC MAG-D03-64)
I 10:12:33 Destination Media Supported Write Speeds: 2,4x; 4x; 6x
I 10:12:33 Destination Media Sectors: 4 173 824
I 10:12:33 Write Mode: DVD
I 10:12:33 Write Type: DAO
I 10:12:33 Write Speed: 2,4x
I 10:12:33 DVD+R DL Reserve Track: No
I 10:12:33 Link Size: Auto
I 10:12:33 Lock Volume: Yes
I 10:12:33 Test Mode: No
I 10:12:33 OPC: No
I 10:12:33 BURN-Proof: Enabled
I 10:12:33 Write Speed Successfully Set! - Effective: 3 324 KB/s (2,4x)
I 10:12:33 Book Type Setting: N/A (Reason: Invalid Command Operation Code)
I 10:12:33 Optimal L0 Data Zone Capacity: 1 897 312
I 10:12:33 Optimal L0 Data Zone Method: ECC Block Boundary
I 10:12:33 Set L0 Data Zone Capacity Succeeded!
I 10:12:35 Filling Buffer... (80 MB)
I 10:12:36 Writing LeadIn...
I 10:13:00 Writing Session 1 of 1... (1 Track, LBA: 0 - 3794607)
I 10:13:00 Writing Track 1 of 1... (MODE1/2048, LBA: 0 - 3794607)
I 10:13:00 Writing Layer 0... (LBA: 0 - 1897311)
W 10:14:52 Failed to Write Sectors 138432 - 138463 - Reason: Write Error
W 10:14:53 Retrying (1 of 20)...
W 10:14:53 Retry Failed - Reason: No Seek Complete
W 10:14:53 Retrying (2 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (3 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (4 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (5 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (6 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (7 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (8 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (9 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (10 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (11 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (12 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (13 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (14 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (15 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (16 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (17 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (18 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (19 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:14:53 Retrying (20 of 20)...
W 10:14:53 Retry Failed - Reason: Invalid Address For Write
W 10:15:19 Retrying (21)...
W 10:15:19 Retry Failed - Reason: Invalid Address For Write
E 10:15:23 Failed to Write Sectors 138432 - 138463 - Reason: Write Error
E 10:15:23 Next Writable Address: 0
I 10:15:23 Synchronising Cache...
W 10:15:27 User opted to skip the 'Close Track/Session/Disc' functions.
E 10:15:27 Failed to Write Image!
I 10:15:27 Exporting Graph Data...
I 10:15:27 Graph Data File: C:\Users\Georges\AppData\Roaming\ImgBurn\Graph Data Files\HL-DT-ST_DVDRAM_GT32N_AS01_DIMANCHE-13-JANVIER-2013_10-12_CMC_MAG-D03-64_2,4x.ibg
I 10:15:27 Export Successfully Completed!
E 10:15:27 Operation Failed! - Duration: 00:02:54
I 10:15:27 Average Write Rate: 1 949 KB/s (1.4x) - Maximum Write Rate: 3 359 KB/s (2.4x)
Thanks again !