Hi, I have used Avast! for a while now. I have two problems. One, I recently tried to install Grisoft's AVG, but I could not. There was an error during installation, when a 16-bit subsystem started to do something in the process installation...it had failed. I believe Avast! scans 16-bit and 32-bit subsystems in the Resident Scanner. Two, I also recently tried to insall ESET's Nod32, but failed. This is a mystery because once installation was done and computer was restarted, it would start up. I use Win XP Home and when it restarts, It becomes stuck on the Window's XP's "Windows is starting up" screen. I have to manually reboot again using the power button, but windows will not register that as a problem because safe mode in not an optioin in boot menu. Sorry for this post to be loing.