Motherboard going bad??

Hey guys, I am having some issues that I am about at wits end with. Before I get into the problem my rig consists of: Asus m2n32 sli deluxe motherboard, amd x2 6000+, evga 880gts (g92) 4 gig of Corsair XMS2 dual channel ram DDR2-8oo (4x1 gig sticks) and Vista home media 32bit. I have had my system for almost 2 years now. I haven't experienced any major problems at all over that time span. In the last week or two I have been getting 2 seperate BSOD's IRQL NOT LESS OR EQUAL and win32k.sys. I have been researhing the two errors and they seem to both lead back the memory. I have removed all 4 sticks and ran them one at a time with memtest and haven't had any errors on any of the sticks. I am also up and running only using one stick. Here is were it gets strange. When I put 2 sticks in slots a1 and b1 (yellow slots) it shows as only having one stick in the motherboard. I have done this with a combination of all 4 sticks and get the same results. I have tried to reseat them and they are in place. When I put all 4 sticks in and hit the power button I dont even post. Everything is coming on as far as fans,ps,hd,vid card and so forth. I also get the no signal on my monitor with all 4 sticks in at the same time. I haven't added any new hardware before this started to happen. Hey guys any ideas or suggestions would be greatly appreciated.