Grammatical Fuckwittery

I was just reading a post on a page I follow. The question was: What grammatical rules do you struggle with?

Where does the list begin? 

Here's my top five:

1. Remembering that adjectives are hyphenated before a noun but not as nouns (stained-glass window, the stained glass). 
2. I often find myself editing sentences where I spend far more time than I should figuring out if it's 'and I' or 'and me.' 
3. Capitalisation, and what counts as a true noun, annoys me like nothing on earth. I don't care what anybody says - it's internet. 
4. All right (because everyone known in a decade it's going to be alright, right?).
5. The fuckwittery between US and UK English, especially enrolled/enroled (US/UK) when it's the other way around for traveled/travelled (US/UK) - I mean, seriously, WTF?

Drop a comment and let me know yours.