The adobe support forums for photoshop are full of good troubleshooting advice too. If your problem is reproducible and the suggested simple measures don’t work, I’d head there and search or ask around. Chances are that you aren’t the first to have your particular problem.
Sounds like reasonable specs to me. It is not often that I have to create files with those dimensions but it happens sometimes and never had such problems.
Which Photoshop are you using and did you experience this before?
Did you try to change the scratch disk to a different hard drive? And you can also try to set the cache level higher