After having had to disable the FW due to it’s slowing down my PC up to a halt over time (12 + hours running) I sadly had to un-install it when it now started messing around with WinAmp (leading to 3 useless CDs) as well as increasing CPU-usage of Diskeeper, uTorrent and JDownloader…back to 4.8 for now, which has never caused me any problems and always protected my PCs.
Hope that things will get sorted out soon ;D
Just an FYI, you can do a custom install with AIS to select not to install the Firewall and/or Spam.
That’s what I did because of the 50% off price of the AIS (which is good for 3 PCs) was less buying Pro for 3 PCs. Been running on all three of my PCs without any problems/issues.
Screen shot below from the AIS Quick Start Guide.
lol you can use the avast free I can assume you it is very light!
Lighter than avast 4.8
With 4.8 I had Pro on one PC and Home on the other two PCs, since there was very little difference between the 4.8 versions of Home and Pro, and the fact that avast! did not provide any type of an competitively priced 3-User Pro license–basically had to buy licenses for three PCs and cost more than many of the other security suites! 
(e.g., Norton, KAV, BD, etc.)
If I’m going to use and rely on an software on a daily basis, I’ll buy a license or make a donation to the dev to support the software. I do not work for free, and do not expect others to so either.
I like having the Sandbox and the other benefits of Pro 5, and I thought the price of AIS with the 50% discount was a good enough deal that I purchased for three years. When the 3 years are up, if the AIS renewal price is not competitive with the other major AVs, may go back to using Home on the other PCs or switch to one of the other AVs.
What other security software are you using? What firewall and antivirus before avast!? This sound like another conflict with the residue of something that was not completely removed by the windows add/remove program procedure.