My Mac Pro 2.66 Quad core has been randomly freezing up lately in a variety of programs, such as Motion , FC 6, Photoshop CS3 or even Safari. Ocassionally I run Parrallels with XP.
I am running 10.5.6. with 10GB ram. I also have a Blackmagic Intensity pro card installed. I've run the system software updater and it hasn't helped. I'm thinking one of the programs was updated and isn't compatible with some of the others.
There are lot of things that could potential cause a machine to freeze up. It could be caused by hardware or by software. Because there are so many potential causes it would be extreamly dificult to troubleshoot the thing over the Internet. I recomend making an appointment at the Genius Bar at your closest Apple Store and let them properly troubleshoot it in person.
There are no "technical solutions" to your "artistic problems".
Don't let technology get in the way of your creativity!