DVD burning problem using nero7 and Win DvD?

Just until 2 days ago my DVD burner worked perfectly.But now,every time i try to burn a DVD( home made videos), all goes fine until it comes to writhing leads- in and burning failed.I waste already 20 empty disks but always same.I use full version of Nero,not trial and also get same result using WinDvd ,also full version.I have disabled my anti-virus protection prior to burning but same results.Before,even anti-virus was running i never had problem while burning DVDs.Any help?I include log file recorded while trying to burn a DVD with Nero.Thanks

[08:23:41] NeroVision Log created (Date: 07/08/2006)

[08:23:48] NeroVision Processors: 1 (Intel)

[08:23:48] NeroVision OS: Windows XP Media Center Edition

[08:23:49] GCCore Detected DirectX Version: 9.0c

[08:23:52] ExpressUI Running Nero Vision Version: 4.5.0.15

[08:23:55] MMTools SourceBuilder: building c:\Documents and Settings\sasha\My Documents\My Pictures\dvd funny videos\joan.mpg video/0

[08:23:56] MMTools SourceBuilder: --- used source filters ---

[08:23:56] MMTools %26#123;E436EBB5-524F-11CE-9F53-0020AF0BA770%26#125; - File Source (Async.)

[08:23:56] MMTools %26#123;A336CD3B-599C-4F70-A34D-E88EDE4B64C3%26#125; - Nero Splitter

[08:23:56] MMTools %26#123;FEB50740-7BEF-11CE-9BD9-0000E202599C%26#125; - MPEG Video Codec

[08:23:56] MMTools SourceBuilder: file type MPEG1 - video

[08:23:56] MMTools --------------------

[08:24:17] MMTools SourceBuilder: building c:\Documents and Settings\sasha\Desktop\2006_07_04\MVI_04... audio/0