I also hooked it up with a Dell 30" display 90% of time using Apple's $100 dual-link DVI adapter. The adapter fails 3-4 times a day - display loses signal for a couple of second and then back to normal. It happens to another normal MBP with another Dell 30" display in our office as well. So the problem probably resides in the adapter not the display nor the laptop. That's probably the worst 100 dollars I was forced to pay in a couple of years.
Why did you opt for the DL-DVI adapter rather than a mini-DisplayPort to DisplayPort cable? I have my rMBP plugged into a Dell U3011 most of the time and this seems like the most straightforward way.
I use an rMBP full time at work as well with no trouble using an Apple thunderbolt display, a 27 inch dell display (via mini displayport), and a fourth 1200p display via HDMI. I'd definitely suggest going for displayport if possible over the finicky DL-DVI adaptors.
I had that problem a few years ago, and it turned out to be a precursor to the adapter failing altogether. I got it replaced under warranty and the new one has been working fine for years. So it might be worth trying to get yours replaced.
