First let me say I am not a computer expert, so someone else may have a more

definitive answer for you. That being said I find that if I don't routinely (like once a week) clear out junk files, cleanup my hard drive and defrag, I will have all kinds of weird glitches. I have been using a program for several years called System Mechanic and without it I would be dead in the water. One of the things it does is clean up your registry. I have found that the bigger the files I work with the more corrupted my system becomes. Working with 400 to 500 meg photoshop files, then rendering in Poser etc. it does not take very long for your system to get out of wack.