I'd been at this non-stop for weeks, and had been just working and sleeping, poring over and over the code with no clue. As I remember it, one night I was dreaming that the code was slowly scrolling up a screen in front of me, and one line was colored red. I woke up at that point and knew what the problem was. I think I just got dressed and went directly into work rather than try to go back to sleep.
Since then, I've had fresh insights after sleeping on a problem and coming back in the next day, but I've never had another instance of my brain saying "It's right here, you idiot!" to me in a dream.
That's something that can be very useful in problem solving. Helps you finding new ideas. The hard thing is grabbing this idea and waking yourself up when you strike gold.
Also, just reading the text itself is alien. Because it's colourful and code-looking, but my mind can't quite get the monospacing right. So outside the direct bit of code I'm looking at, the code gets kinda blurry or wobbly.