Ram issue after reboot from windows!? HELP!

Hello all, I'm having an issue with my MP after rebooting into OSX from windows (vista ultimate). I have an 8-core 2.8 with the 8800gt and I've added a 4g ram kit from Trans Intl (came with 2gig from factory). First off, I originally put the two dimms that it came with down on riser B and put the two new 2gig dimms on the upper riser. Boot up, 6g shows up as installed ram. yay! As soon as I had my mac I installed Vista via boot camp for running Flight Sim. Seems to run fine (thouch wood). Anyway a week or two after having my mac I happen to notice while in OSX that its only saying I have 4g of ram installed! I pulled the ram out, swapped the trans intl to riser B, and stock ram to riser A, no change. Then I put ONLY the trans intl ram in, one dimm on riser A and one on riser B (same placement of dimms as it came with from factory) and it wouldn't boot! It just gave me an error saying I had to restart my mac. This can't be a good sign but the Ram obviously works because it used to show up as 6 gigs! So then I put all 4 dimms back in, the stock ram on riser A and the two Trans Intl dimms on riser B. Reboot and now its back to 6g installed again. Strange...
Last night I went into windows to play some flight sim and now after I restarted back into OSX sure enough only 4g showing up. In my system profiler its showing I have 2 1G dimms on riser A (true) and 2 1G dimms on riser B (not true). Status is OK for all dimms...
Could this be a software issue of some kind or do you think I need to be contacting and sending my Ram back to Trans Intl...

For the record Vista (32 bit) only sees about 2g of ram

Any help would be great! Thanks so much...

 

so far I ran the hardware test as is (with all 4 dims installed) and returned two different codes depending on if I performed the extended test or not.

first test (non extended): 4MEM/4/40000006: B:1 C:1 R:0

extended test: 4MEM/1/40000006: B:1 C:1 R:0

also in the hardware tab under memory it sees all 6 gigs. It looked like this


Dimm1/ Dimm Riser B 1GB 800mhz HYMP512A72CP8D3-S5
Dimm2/ Dimm Riser B 1GB 800mhz HYMP512A72CP8D3-S5

Dimm1/ Dimm Riser A 2GB 800mhz
Dimm2/ Dimm Riser A 2GB 800mhz

not sure why it didn't put a code after the other two 2GB Dimms....

 

I ran the test with just the Apple ram and no errors.

With the Trans Intl ram the hardware test came up with an 'error on startup' but oddly enough when I ran the actual test it said no errors. Actually when I tried to run the first test it froze, then I rebooted and ran the test and it said no errors but did still give me the error on startup message. I can't remember the actual error message but it was something like this
POST / Dimm 1 / Dimm riser A

Also with just the trans intl ram in the box there was a RED LIGHT ON on riser A (upper).

I will check tonight if the red light is on with just the apple ram but I have a feeling it won't be...