I run Avast Free + ‘Internet security’ license. When I updated my avast on my PC, it took forever to start and used to hang regularly. So I restored to the pre-update point. Everything worked fine but no Avast. "No security’ and I could not turn it on.
Being clever (ahem) I downloaded/installed Avast free and applied my license.
The internet stopped working 'No server’message for email and browsers. It was also incredibly slow on my laptop! Clearly avast was doing something to the internet connection.
Even avast license/upgrade reported a connection fail but the router traffic was negligible.
Used a Pro uninstaller to remove avast and now email/ internet is perfect again.
I have lost faith in avast and want a license refund!
Windows 7.
Hi, just to say I had similar problems. Mine was the free month trial Internet Security and I was getting the wheels going round. I tried to uninstall Avast but it has somehow corrupted. It damaged my internet drivers and I had to do a system restor to get them back. Have used Avast Clear but still getting errors message from Avast 
Hi 
AuldMike what AV program,did you use,before Avast? Did you remove them with thier removal tool in safe mode? Use AV removal and completely remove your previous AV. I see you were using 3d part uninstaller to remove Avast,Avast has own removal tool,please use it and remove Avast in safe mode,when you done please download latest version of AIS and report back if you still have problems.
Avast removal tool: http://www.avast.com/uninstall-utility
Avast 9.0.2008: http://forum.avast.com/index.php?topic=139606.0
Thank you
Bye
Downloaded AIS. It took 85 minutes! Installed license. Everything looks good.
Note my last virus checker was Avast Free.
HI Auldmike I hope I got the name right I want you to check and see if you still have avast free on your computer and if you do use the avast removal tool in safe mode again and remove avast free if you do not want it make sure you keep your license for avast internet security in case the removal tool wipes out both avast internet security also.
Go into control panel and got to programs and features and see if you have avast free in the list.
give you some useful advice never run or have more then one real time anti virus on your computer because two real time avs can cause your computer to be slower and it can also crash your computer as well. Have only one real time antivirus at a time on your desktop or laptop at any time.
Have a good day