Hello sg09 and welcome to the forum,
What other antivirus, firewall, trial versions of security software and other security software do you
currently have or had
in the past in this machine? If you had other software in the past, use the vendor's uninstaller tools to remove them (not Revo), but let me know what you currently have in case there may be a conflict.
Avast does
not recommend that you uninstall with Revo, but only with the Avast Uninstall Utility Tool. Therefore, I recommend that you do a complete uninstall of Avast and a clean install:
1. Save a copy of newest version of Avast (5.0.677) for the version you need and save it to your HDD:
Free –
http://files.avast.com/iavs5x/setup_av_free_eng.exe - (English only)
Free –
http://files.avast.com/iavs5x/setup_av_free.exe - (multi-language version)
2. Download the Avast Uninstall Utility, aswClear5.exe
http://www.avast.com/uninstall-utility and save it to your HDD (it has uninstall tools for both 4.0 and 5.0).
3. Disconnect from the Internet at this time.
4. Go to Control Panel and uninstall Avast through Add/Remove Programs if possible and reboot.
5. If Step 4 fails, boot into
Safe Mode (hit F8 repeatedly) and run the Avast Uninstall Tool.
6.
Reboot.
7. Install the newest version of Avast and
reboot.
8. Get Internet access and register your copy Free:
Free –
http://www.avast.com/registration-free-antivirus.php9. Update the Avast definitions.