I'd describe it more in terms of flow (aka being in the zone) & the lack thereof rather than as a design issue. When in that heads space everything just works, when not even the simplest data structure is painful.
As a new full time coder, I experience coder's block perhaps few times a week at the job. I think tomasien's suggestion to write things down is very useful, something I've started doing and help me get through some difficult problems.
Specifically, it is helpful for anyone that is solving a problem whose scope is not clearly defined. Writing, instead of talking, helps to map things out and takes out the pressure in verbalizing an eloquent solution / interpretation, which usually comes a lot later in the problem solving process.