As Spiritsongs mentioned it is possible that it could be malware, so it would be worth running ewido from safe mode.
This gives an indication that there may have been a problem with the install.
"29.07.2006 09:55:44 general: Install check: 'C:\Program Files\Alwil Software\Avast4\ashDisp.exe' does NOT exist." and " 29.07.2006 09:56:10 general: progress end - forced."
Now why this happened malware of corrupt installation file is anyone's guess, that is why I suggested download the latest version of avast again.
Using the same suspect file you downloaded earlier won't eliminate one possibility/cause, so I don't believe removing and reloading the program using this setup/installation file is a good idea. avast will let you uninstall and reinstall till you are blue in the face with the home version.
What avast processes are running in Task manager (see image) ?
Download and run ewido and let us know what if anything it finds.
Download the latest version of avast as your avast and save it to your HDD.
Download the avast! Uninstall Utility,
find it here and save that to your HDD.
Then uninstall, reboot, run the uninstall utility, reboot, install avast using the new setup/installation file, reboot.