When I installed the software and restarted my pc, the program did not install an icon in my system tray. Therefore, I can not enter the code the way I am supposed to…right click, properties, etc. Any thought on how I can get the icon to appear in my tray? When I try to enter the code my double clicking on the desktop icon is when the invalid code appears??
If the ‘a’ icon (blue ball) in the system tray does not appear, avast! is not well instaled…
What is your OS?
What version of avast! do you have installed?
Do you have any other antivirus application installed right now in your system?
Any error window or pop up appeared when setup failed?
What language of avast! are you using? Just English?
Do you use any proxy filter, firewall or any spyware block application?
To help you, we need to know a little bit more about your problem… 8)
My OS is Windows XP
Avast Version 4 (latest)
No other anti-virus protection
A pop up window that said code was not valid
English
The firewall that is in XP is being used
Spyware block is in use as well
Vinny,
Is this a silly question… have you tried re-installing Avast (after properly de-installing of course 
)
W.
My OS is Windows XP
Me too, XP PRO SP1
Avast Version 4 (latest)
Which number?, please, the last is 4.1.315 18th Dec 8:46 (GMT -3)
No other anti-virus protection
Not even in the past? I mean, one that you already desinstalled?
A pop up window that said code was not valid
Why don´t you re-register Avast Home?
English
Today, a new version of avast! will be released at 10 languages!
The firewall that is in XP is being used
Me too, not seem to bring trouble, anyway, you could make a test disabling it
Spyware block is in use as well
Which program?
Anyway, Walker’s suggestion is very good…