Dear Angeman,
Why is capitalisation of letters in Comments boxes so damn tricky? Sometimes a leading character refuses to be capitalised, sometimes it takes a number of tricks to type 'iPod' or any other iApple name correctly. The same for acronyms. It's OK for ordinary people, but for obsessives like me it makes for frustration
It's because the field has an autocomplete function and is filling it in according to a previous entry you have made or a mistake you made initially. The workaround I use is if I've made a capitalization mistake I clear the field and hit return to remove any autocomplete and then retype the entry correctly.