Have installed Avast 4.8 Home (32 bit) on one of my machines two days ago, registered with Avast provided license key and am running the latest updates.
While the on-access protection control seems to working fine, I am unable to run the Antivirus program irrespective of whether I try to run it through the Avast! tray icon (Option - Start Avast! Antivirus) or from Start->All Programs->Avast! Antivirus.
I do get the Avast splash screen which shows memory and startup tests being carried out and once these initial tests are done the splash screen just disappears - and then nothing happens. If I then check Windows Task Manager, it doesn’t show any Avast! application running (under Applications) but it does show the AshSimpl.exe process running (under Processes). I am assuming here that AshSimpl.exe is the process for the Avast! simple user interface.
The machine is a Compaq Presario 2200 series (pretty old model) with PentiumM 1.6GHz, 768MB RAM running Windows XP Professional with SP3.
I had Kaspersky Internet Security (ver 7) installed earlier, which I had removed using “Add/Remove Programs” before I installed Avast! Home.
Interestingly, inspite of having uninstalled Kaspersky from the machine, Windows Security Center is telling me that I have Kaspersky Firewall installed and running (still) ??? This is surprising (to me) because I had uninstalled the software (Kaspersky), rebooted the machine, removed Kaspersky directories from Program files folder, rebooted machine again - before getting to installing Avast!
You may have to do an uninstall of Avast, then Re-install after running their uninstaller.
After that, you should be ok to go. EDIT
I may be wrong about the previous link. It looks like you had version 7 installed, in which case, you should take a look at this page, and follow Kaspersky’s directions to remove their program. The link is here: http://support.kaspersky.com/faq/?qid=208279463