i'm also having this problem, i have a 4 year old dell dimension 4600. i tried to install some ram and i did it incorrectly, so i replaced with the original ram that was in the computer. and with both attempts it goes verrry slow taking 25 minutes to boot up. Geek Squad said that the harddrive may be going bad but i didn't wanna believe them when i just spent soo much money rebuilding (wireless int, graphics card, and new ram) and when i attempt to go into safe mode it locks up and takes the same amount of time to boot.