[QUOTE=bjchad;7393119]Check to see if your thread is hanging up somewhere. If the spool has a notch for tucking in the loose end, make sure that the thread isn't coming off that end of the spool.QUOTE]
I was going to suggest that about the notch on the spool. That has happened to me several times. Now I know to thread my machine with that notch is facing opposite of where the thread comes off.
You might also just take the thread & see how easily it hand breaks. Just take it & try to break it by hand. If it breaks fairly easily it might be old thread that is deteriorating.