Just checked, it still refuses to update (manually or auto). Again I uninstalled via control panel, booted, used the uninstall util, booted, reinstalled the latest version, booted, regged it etc. to no avail. Once again I managed to update it only via the "update" option when calling the "add/remove programes" of win control panel. But every time when trying to manually update it hangs with no error message at the "initializing, please wait.." step (1/2 or 1/3). And the autoupdate doesn't work, the defs remain at April 14th and I'm not getting any notifications that the system was updated (which used to happen at least once a day). I'm always using admin account on my XP SP3 (fully updated) system. Also using COMODO firewall, spybot S&D, ad-aware, malwarebytes antimalware (all of the above were installed for more than a year and I never had any conflict with Avast 4.8 or 5). I even manually added as permitted on comodo, all of the .exe files in the avast folder. The way the manual update process is halted makes me think that somehow the updater doesn't actually connect to avast's site in order to get any updates (while it still works when I try updating via the add/remove programs).
Copying from PCWizard (if you need more detailed specs on my system let me know)
Mainboard : MSI MS-7502
Chipset : Intel P31/P35
Processor : Intel Core 2 Quad Q8200 @ 2333 MHz
Physical Memory : 4096 MB (2 x 2048 DDR2-SDRAM )
Video Card : NVIDIA GeForce 9600 GT
Hard Disk : WDC (1000 GB)
Hard Disk : Hitachi (1000 GB)
Hard Disk : Seagate (1000 GB)
Hard Disk : WDC (1000 GB)
DVD-Rom Drive : HL-DT-ST DVDRAM GH20NS10
DVD-Rom Drive : YFIZO Y7WLIRGTU7GH SCSI CdRom Device
DVD-Rom Drive : YFIZO Y7WLIRGTU7GH SCSI CdRom Device
Monitor Type : GM2600 - 25 inches
Network Card : 82562V-2 10/100 Network Connection
Network Card : 82562V-2 10/100 Network Connection
Operating System : Microsoft Windows XP Professional 5.01.2600 Service Pack 3
DirectX : Version 9.0c (ÌÜñôéïò 2009)