Did you try increasing your virtual memory? I always heard that you should have a 1:1 for your combined card memory. So in your case I'd go with 64gb. On a 120GB hard drive that might be difficult. Personally I have 500GB SSD on each of my rigs. Maybe you can add another cheap SSD and just use that for VM?

You could also try just enabling one card at a time and see how many work?
Miner Properties > GPU Selection at the bottom > Use selected from list > (Select just one or two then hit OK) > See if it runs (stable.) If so, add another until it stops.

I also use Awesome Miner for all of my rigs and I'm not having any issues with Claymore 15. Alternatively, try PhoenixMiner. If you have the same problem then it's probably not with the software.