PC Problem. Need some Advice Hi guys. My home is using a Dell PC shared by my 2 brothers.. The first few months of use were rather smooth. quick start-up and loading of programs. the com became real slow suddenly recently.. The boot up time was around 15mins. From pressing the on button to opening up to the OS to waiting for all the pre-program to load up. The pre loading at the startup was really really slow. took about 14mins the last time i timed. I checked for spyware, virus and even cleaned up registry using the CCleaner. The computer is still very slow during the start up. The Harddisk still got tons of space. My Guess was the installation of Norton Anti Virus by my brother. I have heard before that 2 anti virus program will crash the whole system. Wonder if this is true. Or is there other things that might made the boot-up into snail-like pace? what are the options do i have? Should i reformat the PC ?