Interestingly enough, I find that I get the most frustrated in this kind of sense when i've had a break from music and I come back to it. I recently went overseas and didn't have the opportunity to work on music while overseas, because although I had a laptop at my disposal I was simply unable to make time to use it. Since i've gotten back home, i've finished two tracks, however I noticed that for the first track it was somewhat of a struggle to come up with a coherent yet creative idea and finish it off.
Instead of quitting though, I finished the track and tolerated this sense of frustration which made the process much easier for the following track.
Why? That's an interesting question to think about. I think that it has to do with creativity coming from a sort of frustration. Only by being frustrated at a percieved lack of progress can you let go enough to make progress. By this i'm referring to letting go of your idea of perfection. Even if it's only on a subconscious level, trying to conform to your idea of perfection means you're censoring your ideas before they have a chance to get out and be developed into something worth keeping. In short, you're expecting that ideas will be conceived of fully formed, which in a musical sense almost never happens.
You need to repeat the process of coming up with creative ideas, and recognise that this is the part that's really important, the ideas themselves will improve with the repetition of the process. Another way to phrase this would be that you've let the balance swing away from chance and towards control, when in reality you need an equal amount of both. I want an ordered final product, one that people will be able to relate to, but I want this to come about by chance so that it's creative and unique.