Cant Instal Avast or Ad aware on Laptop?

Boot into Safe Mode by pressing(tapping) the F8 or the DELETE key depending on your computer. Select Safe Mode With Networking. Go to Control Panel and then Add/Remove Programs and uninstall any old anti-virus or spyware programs you have installed. Then reboot the computer and boot back into Safe Mode. (Make sure you are not connected to the internet). Disable any firewall you have running and then install the Anti Virus software and perform a full scan of the computer (don't) bother updating now you will do it later). Next install the anti-spyware program and scan for spyware. After you are done. reboot the computer normally. Hope this helps!