Upgradation / Installation Problem !

I am using Avast free antivirus for the last 1 year and i am quite satisfied with it.
My current operating system is Windows XP with SP3.
Currently i am using Avast Free adition version 6.0.1367.
For the last 1-2 months i am trying to update the Free Avast to 7 but did not succeed.
When i try to upgrade it from the avast antivirus it gives message Initializing please wait. But after that nothing happens.
I also tried to download the latest setup from the website but when i run the set it gives me error "Error reading product data from file c:\program…\setup. Setup cannot continue.

Please help me in this regard.

Download the latest 7.0.1466 from here http://forum.avast.com/index.php?topic=103687.msg830212#msg830212 and save, then uninstall the version you have now, reboot and install the saved copy.

If you have troubles removing avast then use the removal tool from here http://www.avast.com/uninstall-utility and run in safemode, when completed reboot and install saved copy.