Thank you for Avast Free! I have Windows7 64-bit on a HP laptop. When I try to add or remove components of Avast Free using Ctrl-Panel's "Programs and Features", whenever I exit I always get the compatibility-oriented message from Windows: "Did this program install properly?".
did you remove Your previous used AV before installing avast? did you computer come With a factory preinstalled AV (hp usually come With Norton/Symantec) was this removed before installing avast?

General: Uninstalling a third-party antivirus software http://www.avast.com/faq.php?article=AVKB11#artTitle