Sony Vaio Keyboard light never turns off

After some investigation, I found the culprit: I had been using a custom keyboard layout that disabled dead keys, and apparently it also forced the usage of the Shift key to turn off caps-lock (ShiftLock as some call it).

I had tried switching to the default layout before and it didn't seem to work, now I realize that probably was because I had tested on an existing Notepad window instead of opening a new one.

Solution: I downloaded MSKLC and created a new layout based on that one but without enabling ShiftLock.

Here's a way to recover from the keyboard being stuck without losing everything:

1. Use CTL + ALT + DEL (if it still works, or you can use the mouse and the start menu) to get to the logout/change user menu
2. Change user to yourself

This resets the keyboard, while retaining your the running programs. You don't lose anything except your temper.

This is not a cure to that prevents the keyboard from sticking, so I'm not marking this as the accepted answer.