I have never had problems with the Korean language on my computer until just about a week ago.
Korean has been turning into boxes on applications such as iTunes, notepad, and on the tabs of Google Chrome. It also turns into boxes for Twitter. However, in Facebook, certain websites, and Microsoft Office applications, I have no problem with typing or reading Korean.
I've tried going to C:/Windows/System32 and deleting the FNTCACHE.dat file and after rebooting my computer everything turns back to normal. However, the problem eventually reoccurs and I'd prefer a solution that doesn't require me to do this every once in a while.