Same issue here. Started today.
Log file: (Just last few from today Nov 20 2012)
20.11.2012 12:37:50.000 1353433070 (null) Used server:
http://download119.avast.com/iavs5x20.11.2012 12:37:50.000 1353433070 (null) GetFileWithRetry: prod-ais.vpx downloaded .
20.11.2012 12:37:50.000 1353433070 (null) prod-ais.vpx not changed, 1353313485
20.11.2012 12:37:50.000 1353433070 (null) LoadPartInfo: jrog = jrog-a7 returned 00000000
20.11.2012 12:37:50.000 1353433070 (null) LoadPartInfo: jrog2 = jrog2-653 returned 00000000
20.11.2012 12:37:50.000 1353433070 (null) LoadPartInfo: program = prg_ais-5c2 returned 00000000
20.11.2012 12:37:50.000 1353433070 (null) LoadPartInfo: setup = setup_ais-5c2 returned 00000000
20.11.2012 12:37:50.000 1353433070 (null) LoadPartInfo: vps = vps_win32-12111900 returned 00000000
20.11.2012 12:37:50.000 1353433070 (null) Part vps_win32-12111900 was set to be installed
20.11.2012 12:37:50.000 1353433070 (null) Part jrog2-653 was set to be installed
20.11.2012 12:37:50.000 1353433070 (null) Part prg_ais-5c2 was set to be installed
20.11.2012 12:37:50.000 1353433070 (null) Part vps_win32-12111900 was set to be installed
20.11.2012 12:37:50.000 1353433070 (null) Part setup_ais-5c2 was set to be installed
20.11.2012 12:37:50.000 1353433070 (null) Part jrog-a7 was set to be installed
20.11.2012 12:37:50.000 1353433070 (null) Part jrog2-653 was set to be installed
20.11.2012 12:37:50.000 1353433070 (null) IsFullOkay: jrog2-653.vpx - not okay (doesn't exist)
20.11.2012 12:37:50.000 1353433070 (null) IsFullOkay: jrog2-653.vpx - not okay (doesn't exist)
20.11.2012 12:37:51.000 1353433071 (null) InvalidateCurrent: invalidated server 'Download119 AVAST5 Server' from 'main'
20.11.2012 12:37:51.000 1353433071 (null) SelectCurrent: selected server 'Download364 AVAST5 Server' from 'main'
20.11.2012 12:37:51.000 1353433071 (null) SYNCER: Type: use IE settings
20.11.2012 12:37:51.000 1353433071 (null) SYNCER: Auth: another authentication, use WinInet
20.11.2012 12:37:51.000 1353433071 (null) Server returned 404 on file jrog2-653.vpx
20.11.2012 12:37:51.000 1353433071 (null) InvalidateCurrent: invalidated server 'Download364 AVAST5 Server' from 'main'
20.11.2012 12:37:51.000 1353433071 (null) SelectCurrent: selected server 'Download121 AVAST5 Server' from 'main'
20.11.2012 12:37:51.000 1353433071 (null) SYNCER: Type: use IE settings
20.11.2012 12:37:51.000 1353433071 (null) SYNCER: Auth: another authentication, use WinInet
20.11.2012 12:37:51.000 1353433071 (null) Server returned 404 on file jrog2-653.vpx
20.11.2012 12:37:51.000 1353433071 (null) InvalidateCurrent: invalidated server 'Download121 AVAST5 Server' from 'main'
20.11.2012 12:37:51.000 1353433071 (null) SelectCurrent: selected server 'Download349 AVAST5 Server' from 'main'
20.11.2012 12:37:51.000 1353433071 (null) SYNCER: Type: use IE settings
20.11.2012 12:37:51.000 1353433071 (null) SYNCER: Auth: another authentication, use WinInet
20.11.2012 12:37:51.000 1353433071 (null) Server returned 404 on file jrog2-653.vpx
20.11.2012 12:37:51.000 1353433071 (null) tried 3 servers to get file 'jrog2-653.vpx', but failed (0x20000006)
20.11.2012 12:37:51.000 1353433071 (null) DldPackage: C:\Program Files\AVAST Software\Avast\Setup\jrog2-653.vpx, returned 0x20000006
20.11.2012 12:37:51.000 1353433071 (null) LoadAllDefs failed 0x20000006
20.11.2012 12:37:51.000 1353433071 (null) FilterOutExistingFiles: 486 & 481 = 5
20.11.2012 12:37:52.000 1353433072 (null) IsFullOkay: vps_32-95d.vpx - not okay (doesn't exist)
20.11.2012 12:37:52.000 1353433072 (null) IsFullOkay: vps_32-95d.vpx - not okay (doesn't exist)
20.11.2012 12:37:52.000 1353433072 (null) IsFullOkay: vps_win32-970.vpx - not okay (doesn't exist)
20.11.2012 12:37:52.000 1353433072 (null) IsFullOkay: vps_win32-970.vpx - not okay (doesn't exist)
20.11.2012 12:37:52.000 1353433072 (null) IsFullOkay: vps_win64-600.vpx - not okay (doesn't exist)
20.11.2012 12:37:52.000 1353433072 (null) IsFullOkay: vps_win64-600.vpx - not okay (doesn't exist)
20.11.2012 12:37:52.000 1353433072 (null) IsFullOkay: jrog2-653.vpx - not okay (doesn't exist)
20.11.2012 12:37:52.000 1353433072 (null) IsFullOkay: jrog2-653.vpx - not okay (doesn't exist)
20.11.2012 12:37:52.000 1353433072 (null) FilterOutExistingFiles: 486 & 481 = 5
20.11.2012 12:37:52.000 1353433072 (null) m_bOperationDidSomething 481/486/6426
20.11.2012 12:37:52.000 1353433072 (null) Error:Other HTTP error (404), while trying 77.234.41.39:80//iavs5x/jrog2-653.vpx
20.11.2012 12:37:52.000 1353433072 (null) Transferred: files 5, bytes 0, time 13543 ms
20.11.2012 12:37:52.000 1353433072 (null) Retries: total 3, files 1, servers 5
20.11.2012 12:38:13.000 1353433093 (null) Sending stats '
http://stats7.avast.com/cgi-bin/iavs4stats.cgi': 00000000 204
20.11.2012 12:38:13.000 1353433093 (null) NeedReboot=false
20.11.2012 12:38:13.000 1353433093 (null) Return code: 0x20000006 [Other HTTP error (204), while trying 74.86.125.45:80//cgi-bin/iavs4stats.cgi]
20.11.2012 12:38:13.000 1353433093 (null) Stopped: 20.11.2012, 12:38:13