Impossible de supprimer avast

Bonjour,
j'essaie depuis quelques heures de désinstaller "avast" en vain....
a peine je clique sur "désinstaller" dans le panneau de configuration qu'un message apparait disant "il y a eu une erreur pendant la désinstallation du produit"
avec un journal d'erreur remplis de codes, pouvez-vous me venir en aide s'il vous plait, je ne pourrai pas installer de nouveaux antivirus sans supprimer avast....
merci a vous d'avance !



voici les codes :



03.01.2011 16.55.17 general: Started: 03.01.2011, 16:55:17
..................................general: Running setup_ais-1fb (507)
..................................system: Operating system: windows vista ver 6.0, build 6000, sp 0.0 x64

..................................system: memory: 38% load. phys:1048575/1048575k free, page:1048575/2097151k free, Virt:2012620/2097024k free

..................................system: computer winName: RICHARD-PC
..................................system: windows Net User: RICHARD-PC\jenna
..................................general: Cmdline: /uninstwiz
..................................general: Old version: 1fb (507)
..................................system: Using temp: C:\Users\jenna\appData\local \Temp\_asw_aisI.tm_a08104 (514193M free)

....................general: SGW32AIS: :CheckIfInstalled set m_bAlreadyInstalled to 1
.........general: DldSrc set to inet
.....internet: SYNCER: Agent=Syncer/5.00 (ais-507;p)
..system: computer DnsName: RICHARD-PC
system: computer Ip Addr: 192.168.0.12
system: Installed in: C:\program Files\alwil software\avast5 (514193M free)
internet: SYNCER: type: use IE settings
internet: SYNCER: auth: another authentication, use WinInet
package: part prg_ais-252 is installed
package: part vps_win32-11010201 is installed
package: part setup_ais-252 is installed
package: part jrog-a7 is installed
general: loadstate: edition=1
general: old version: 1fb (507)
file: SetExistingFilesBitmap: 360->98->98
general: GUID: e337b10b-0087-4b7f-917a-84b800f56e8b
general: server definition(s) loaded for 'main': 376 (maintenance:0)
general: selectCurrent: selected server 'download894 AVAST5 Server' from 'main'
internet: SYNCER: Type: use IE settings
internet: SYNCER: auth: another authentication, use WinInet
general: Operation set to INST_OP_UNINSTALL
general: entered SetupProcessAIS: :Do ( INST_OP_UNINSTALL )
general: entered SetupProcessWin32Avast: :Do ( INST_OP_UNINSTALL )
package: transferred: files 0, bytes 0, time 0 ms
package: Retries: total 0, files 0, servers 1
internet: sending stats 'http://download894.avast.com/cgi-bin/iavs4stats.cgi' : 00000000 204

file: NeedReboot=false
general: Return code: 0x000004c7 [L'operation a été annulée par l'utilisateur.]
general: Stopped: 03.01.2011, 16:55:26