Hi
I have not heard of this before. As it is working on all other applications the only thing I can think of is you may have an empty macro that has a shortcut key of Left Arrow assigned to it. This would, in effect, disable the left arrow in MS Word. You mighy ask why anyone would create an empty Macro with the left hand arrow as a shortcut, well stranger things have happened.
I will share a short and funny story with you to prove my point. I used to work for an accounts company who wanted to computerise their accounting system so they had a trial version installed. For three months our Financial Director failed to get it to work so he called in the supplier. The Supplier simply went to the back of the screen and turned the brightness up and lo and behold there was the accounts system in full view. This really is a true story.
The moral of this story is don't assume no one will do silly things, we ALL do them at some point.
Good luck.
Tony (OTPM)