So, my Mac Pro is all of a sudden now going really slow even if I'm just doing simple things like opening an email window. I went to About This Mac and it's now got me listed as only have 2gb of RAM as opposed to 4GB. I have 4 1GB sticks, 2 matching sticks in each Riser. I opened up the computer and rechecked that they were all connected securely. Is it possible 2 of my sticks are not reading all of a sudden? I seem to remember it actually telling me on About This Mac that it recognized 4GB of ram. And, it seems things have drastically slowed down and making that god awful "im working" noise all the time.