When I tried to repair Avast this is what the debug report said:
20.04.201220:25:22general:Started: 20.04.2012, 20:25:22
20.04.201220:25:22general:Operation set to INST_OP_UNKNOWN
20.04.201220:25:22general:Old version: 592 (1426)
20.04.201220:25:22internet:SYNCER: Agent=Syncer/5.00 (ais-1426;p)
20.04.201220:25:22general:Running SETUP_AIS-592 (1426)
20.04.201220:25:22system:Operating system: Windows Vista ver 6.0, build 6002, sp 2.0 [Service Pack 2]
20.04.201220:25:22system:Memory: 44% load. Phys:1166876/2086596K free, Page:3266388/4194303K free, Virt:2017196/2097024K free
20.04.201220:25:22system:Computer WinName: JASON-LAPTOP
20.04.201220:25:22system:Windows Net User: Jason-Laptop\Jason
20.04.201220:25:22general:Cmdline: /uninstwiz
20.04.201220:25:22general:Old version: 592 (1426)
20.04.201220:25:22registry:Deleted registry: Software\AVAST Software\Avast\UpdateReady
20.04.201220:25:22system:Using temp: C:\Users\Jason\AppData\Local\Temp\_asw_aisI.tm~a04680 (82151M free)
20.04.201220:25:22general:SGW32AIS::CheckIfInstalled set m_bAlreadyInstalled to 1
20.04.201220:25:22general:DldSrc set to inet
20.04.201220:25:22internet:SYNCER: Agent=Syncer/5.00 (ais-1426;p)
20.04.201220:25:22system:Computer DnsName: Jason-Laptop
20.04.201220:25:22system:Computer Ip Addr: 10.0.1.5
20.04.201220:25:22system:Setup GUI DLL not found at location: C:\Users\Jason\AppData\Local\Temp\_asw_aisI.tm~a04680\SetupGUI.dll
20.04.201220:25:22system:Setup GUI has been successfuly loaded from EXE.
20.04.201220:25:22system:Installed in: C:\Program Files\AVAST Software\Avast (82151M free)
20.04.201220:25:22general:LoadState: Edition=1
20.04.201220:25:22internet:SYNCER: Type: no proxy
20.04.201220:25:22internet:SYNCER: Auth: no authentication
20.04.201220:25:22package:Part prg_ais-592 is installed
20.04.201220:25:22package:Part vps_win32-12041800 is installed
20.04.201220:25:22package:Part setup_ais-592 is installed
20.04.201220:25:22package:Part jrog-a7 is installed
20.04.201220:25:22package:Part jrog2-4a5 is installed
20.04.201220:25:22general:Old version: 592 (1426)
20.04.201220:25:25file:SetExistingFilesBitmap: 991->446->445
20.04.201220:25:25general:GUID: af6e7759-5e53-4506-a756-2ddb7684405e
20.04.201220:25:25general:Server definition(s) loaded for 'main': 253 (maintenance:0)
20.04.201220:25:25general:SelectCurrent: selected server 'Download988 AVAST5 Server' from 'main'
20.04.201220:25:25internet:SYNCER: Type: no proxy
20.04.201220:25:25internet:SYNCER: Auth: no authentication
20.04.201220:25:34general:Operation set to INST_OP_REPAIR
20.04.201220:25:34general:Entered SetupProcessAIS::Do( INST_OP_REPAIR )
20.04.201220:25:34general:Entered SetupProcessWin32Avast::Do( INST_OP_REPAIR )
20.04.201220:25:34general:Entered SetupProcessWin32::Do( INST_OP_REPAIR )
20.04.201220:25:34general:Entered SetupProcess::Do( INST_OP_REPAIR )
20.04.201220:25:34general:Entered SetupProcessAIS::Do( INST_OP_UPDATE_INSTALL_PACKAGES )
20.04.201220:25:34general:Entered SetupProcessWin32Avast::Do( INST_OP_UPDATE_INSTALL_PACKAGES )
20.04.201220:25:34general:Entering:UpdateInstallPackages
20.04.201220:25:35general:progress dialog start
20.04.201220:25:35package:LoadPartInfo: jrog = jrog-a7 returned 00000000
20.04.201220:25:35package:LoadPartInfo: jrog2 = jrog2-4a6 returned 00000000
20.04.201220:25:35package:LoadPartInfo: program = prg_ais-592 returned 00000000
20.04.201220:25:35package:LoadPartInfo: setup = setup_ais-592 returned 00000000
20.04.201220:25:35package:LoadPartInfo: vps = vps_win32-12041802 returned 00000000
20.04.201220:25:35package:FilterOutExistingFiles: 446 & 445 = 1
20.04.201220:25:35package:IsFullOkay: vps_32-79b.vpx - not okay (doesn't exist)
20.04.201220:25:36package:SetDownloadBits: vps_32 setting 92 diffs to process
20.04.201220:25:36package:IsFullOkay: vps_win32-7af.vpx - not okay (doesn't exist)
20.04.201220:25:37package:SetDownloadBits: vps_win32 setting 92 diffs to process
20.04.201220:25:37package:IsFullOkay: jrog2-4a5.vpx - not okay (doesn't exist)
20.04.201220:25:37package:SetDownloadBits: jrog2 setting 85 diffs to process
20.04.201220:25:37package:ArePartsInstallable: 0
20.04.201220:25:37package:Error processing packages. 0x20000011