This is not the 'ARGH' you are looking for. It's a different kind.

1) The left shift key is not working with certain keys on the top row of the keyboard. This is even more fascinating/weird than it is frustrating; I cleaned under the shift key a couple times, with no improvement. (And, yes, I'll need a new keyboard if I can't figure out how to fix it -- the right shift key is one I'll have rather more trouble using after surgery, and it's kind of painful to hit even now.)

2) I need to fix the emotional arc in (a relatively small section of) my book. Grr! Argh! This is arguably something I should not be putting off until I'm finished my other revisions, but I think I'll need to give it my time and attention in a way that I can't do when I still have eighty-some pages left to go. But it's interesting -- to the extent that my revisions are going well so far, it's because having a fixable problem is actually a bit exciting. It's the unfixable ones that are a huge pain.