I don't know if this is a site problem or my Firefox but I think I must have touched something.
On some places like while composing an email with Gmail i can't press ctrl left/right to highlight/select words. I notice this at a few places. Here in this post its fine, I'm unsure what the common denominator is in all the places this doesn't work.
-edit- I'm using Firefox 3.6.13. On both profiles i have they both cant use ctrl+left/right. With Google Chrome it works.