Cannot update:Package Is Broken

Virus definitions and program updates will not work,message says “package is broken”!This has not happened in a long time but now I can’t even get the repair module to work in add/remove?Using Firefox 9.1,Avast Free,Vista!Should I do a complete reinstall,any suggestions?

Sounds like your only choice if repair doesn’t work, download latest version of avast http://files.avast.com/iavs5x/setup_av_free.exe and the removal tool http://files.avast.com/files/eng/aswclear.exe and save - uninstall avast from programs and features then reboot into safe mode and run the removal tool for all versions of avast used in the past with reboots inbetween, now reboot into normal mode when finished and install your newly saved avast version, register and reboot.

Make sure you have also removed all leftovers of other AV’s used in the past, run removal tools from here http://singularlabs.com/uninstallers/security-software/

For Vista, be sure to use Windows Updates, several times with reboots in between until no new Windows updates are available. This is specially valid for Vista SP1 and SP2.