Hrm... Well I only HAVE 3 gig's of ram on my system so I can't say what it would do with more ram. I do get a similar apparent freeze when the 64 bit version renders but it's usually just a freeze of the preview window and progress bar but when it's done rendering the progress bar goes away and there's my image. Is all of your memory good and is it all the same? IE: Speed, Brand etecetra... Wish I could help you more but this does sound like a memory handling issue and you have more on your system than I do.