ANY memory errors are unacceptable. Yes, that's why Windows is freezing.
Now you have to figure out why. Your vid card is unlikely to interfere with memory unless it's shorting the data bus. I doubt it since I doubt it would even post. If you have a spare card for testing it wouldn't hurt to eliminate it.
Onboard voltage readings are notoriously unreliable, although if your PSU was out of spec enough to cause problems I'd suspect you'd see something. If you have a spare PSU it would eliminate that possibility. You could also use a digital multimeter ($20 at Radio Shack) to test your voltages (this is the only really reliable way to check your rails). Voltages should be within 5%. For a high-performance system 3% would be better.
Make sure the CPU isn't overheating. Overheating will cause memory errors.
Eliminating all that I would assume the likely culprit is the memory. Not necessarily that it's bad, it's just probably the wrong memory for that board.
I assume this is a dual channel mobo. If so, pulling one stick may allow it to run stable. Dual channel is much fussier about timing. However to be sure it's not defective RAM I'd run MEMTEST with one stick, testing each of the two sticks by themselves.
Assuming you can get it to run stable with one stick then it's just a matter of tweaking the timing and maybe raising the DDR memory voltage slightly to improve stability.
Another issue to be aware of is that for dual channel, both sticks need to be the same. You can't mix and match brands even with the same timing. There are always subtle differences in performance between different memory. For high-performance systems (like gaming or overclocked systems) you should buy MATCHED memory - these are two sticks sold together that have been tested to be a very close match.
This forum is littered with posts by people who made the mistake of buying just any memory that's on sale and ASSUMING that it would work fine on their system. Modern mobos (especially dual channel) are VERY fussy about timing. You should always use a memory manufacturer's online configurator to order memory that's matched to your mobo.
The AN35 is rather notorious for being finicky about memory.
You might get it to run stable by increasing the timing. You didn't mention the manufacturer of your RAM. You might try contacting them and asking them for recommended timing settings. Even simpler, just do a Google search for "AN35-N recommended memory timing" and variations on that. Make sure to also check Google newsgroups. I found this thread which may help:
http://forums.pcper.com/showthread.php?t=364896
Frankly I'd consider selling the memory and ordering some Crucial or Corsair memory that's guaranteed to work with that mobo. Here's a review of Corsair memory on that mobo:
http://www.bigbruin.com/html/crucialddr.htm
If you're planning on doing any serious gaming, I'd recommend at least 1Gb (two 512 sticks).
Hope this helps...