I'm told I shouldn't have installed avast! before I removed norton, because you should never have two antivirus programs running at the same time. I was advised to reinstall avast! because norton could have compromised the install.
This is the Norton/Symantec Uninstaller Tool:
http://us.norton.com/support/kb/web_view.jsp?wv_type=public_web&docurl=20080710133834ENSince Symantec is known to leave remnants behind, you can also go into Safe Mode (hit F8 repeatedly upon boot up), once in Safe Mode go to Advance Search > enter "sym" into the search box and see if anything comes up. Do the same but type in symlcbrd.sys , which is a Symantec Core Service BIOS reader. Do it again but type in Symantec, and again but type in NIS or NAV (depending on what you had installed on the machine). If you are uncertain of the files that come up on the search, right click on the file to show you Properties and you can tell if it belongs to Symantec...if it does you can delete it then empty your recycle bin and restart your machine.
You are correct in that having more than 1 AV on your machine can cause conflicts and possibly corrupt the other AV, so a clean install is suggested of Avast.
1. Save a copy of Avast (for the product you need) and save it to your HDD:
http://www.avast.com/download-software – all products (Free, Pro, AIS)
2. Download the Avast Uninstall Utility
http://files.avast.com/files/eng/aswclear6.exe and save it to your HDD.
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.
Uninstall ALL previous versions and products of Avast at this time.6.
Reboot.
7. Install the newest version of Avast and
reboot.
8. Get Internet access and register your copy or add the license key for Free, Pro, or AIS.
9. Update the Avast definitions.
It is safe to run MBAM (Malwarebytes) either Free or Pro versions with Avast. If you use the Pro (paid) version, you may want to add MBAM to Avast exclusions under Settings and in the Real-time File Shield and Behavior Shield.
You also want to add Avast to your ZA FW trusted exclusions and vice versa. Some users have had problems with ZA FW, but this issue should be resolved now. Should you have problems/conflicts, please report back to us on this issue.
Please report back on how things go and if your issue is resolved. Thank you.