QUOTE(jayjay @ Aug 21 2008, 05:45 PM)

I have a really bad habit of looking at the keyboard when I'm playing.
It is not always bad. If you have memorized a piece there is nothing wrong with looking at your hands as you play it. Switching eyes back and forth between keyboard and score is dangerous, difficult, and tiring. It is very easy to lose your place in the score.
QUOTE(jayjay @ Aug 21 2008, 05:45 PM)

Any large intervals when my hand has to jump across an octave or more, I'll have to look down briefly to see where I'm landing my fingers.
But if you HAVE to look at your hands that is indeed a handicap. CHOOSING to look (for added security) is something else
QUOTE(jayjay @ Aug 21 2008, 05:45 PM)

Does anybody have an effective way of stopping this irritating problem, because I'm convinced I'm not going to get very far if I carry on doing it.
There is no special secret. Find some pieces with the sort of left hand jumps that you are having trouble with. Practice LH slowly. Many repetitions. It is OK to look at the hand to start with. With enough repetitions and familiarity with the movements you'll find that you can judge the leaps without looking. Perhaps you have underestimated the amount of repetition it takes to get some skill at these kinds of thing, or perhaps you have never isolated the problem for focussed practice?
Another useful tip. The LH is often a leap up from a base note with the little finger to a chord. It is useful to practice with reverse thinking. Imagine the higher position of the hand as the "home" and skip down with the little finger.
The basic movement is mainly a forearm movement. Swivelling the wrist and/or striking the note(s) with a tremelo action gives poor control and poor accuracy.
Using a metronome helps. Set at 70 or slower, one note or chord per beat
Finally it can be helpful to keep your hand spread to minimize the distances.
Your teacher should be showing and telling you this stuff.