Booting issue with 4 gigs of memory installed

I put together a system about a month and a half ago with these basic stats:
AMD 5000+ Black with Zalmann Cooler
EVGA 8800GT
Gigabyte GA-M57SLI-S4
4 gigs G. Skill DDR2 800 5-5-5-15 1.8-2.0V
Rosewill 550 Watt PSU

First, I know G. Skill and Rosewill aren't favorite brands, but I am on a budget and atm this is what I can afford. I'll upgrade once I can

A little history: When I first put the machine together it would freeze, bluescreen, and randomly restart regularly. It was the most stable with only one stick of memory installed. Long story short, I RMAed one of the sets of memory (when it failed a mem test regularly) and the mobo (when the RMA memory came back and still didn't work in mobo).

Finally, on to my problem: I put the machine back together with the 4 gigs of memory installed and it froze while booting Vista. I checked and it also froze booting XP. I pulled 2 sticks of memory and it worked fine. I switched both the slots and the memory sticks and it still worked fine, so it isn't 2 sticks of bad RAM. I reinstalled all 4 gigs of memory and changed the voltage from 1.8 to 2.0 and then instead of freezing, my computer restarted while booting windows (both XP and Vista). The bizarre thing is that both Vista and XP will boot fine with 4 gigs of RAM in safe mode... Does anyone have any suggestions for me? Other than this, my comp runs perfectly. Thanks in advance.

Also, do a MB search around the tech forums and find which RAM has the most success with your board. Send G. Skill Tech support an email and ask if they have RAM tested compatible while populating all 4 DIMMS with your MB. Or, run your MB through a configurator like this one to choose RAM guaranteed to run in your board:

http://www.crucial.com/index.aspx? [...] awoddus80w

Bios updates are a must. Otherwise this post has been mostly answered.
Increase northbridge voltage, increase ram voltage, check for bios updates. Not much more to do.

G. Skill support has been good about answering my email support questions, maybe they will gve you some pointers. An increase to your NB voltage would be made in BIOS. It could make the difference.

I had the same problem but solved it by using two 2GB matched sticks instead of 4 sticks. The problem was the one set was revision 2.0 and the other was revision 4.1. No more bsod or games locking up. Now you are aware of the Vista 32 memory limitation. It's being used but you will not the see full amount but don't worry it's being utilized for other purposes.