I am running Windows Vista build 6001 SP1. Since installing Avast 4.8-1296, every time I restart the computer it comes up with Windows Security Centre reporting that Windows Firewall is turned off. If I turn it on, when I restart its back to Firewall turned off.
p.s. I previously had Mcafee antivirus and firewall and uninstalled them from the control panel before installing Avast
Some links that might help depending on what product you had installed.
McAfee has an uninstall tool that you could run to ensure any possible remnants are removed.
http://download.mcafee.com/products/licensed/cust_support_patches/VSCleanupTool.exe Or http://majorgeeks.com/McAfee_Consumer_Product_Removal_Tool_d5420.html
2007 version - http://download.mcafee.com/products/licensed/cust_support_patches/MCPR.exe
Also see - How do I uninstall SecurityCenter? http://ts.mcafeehelp.com/faq3.asp?docid=71525