Spaces in Posts

I’ve had WordPress up for about a month or so and it seems to be working fine. The only problem I get is when I go to write a post from within the webpage itself. If I do this, inevitably, somewhere towards the bottom section of the post, it will start placing large spaces, about a tab or two, in between every word.

I’ve been able to resolve this by writing the post in MS Word and then copying it onto the webpage. Anyone know whats wrong with my wordpress?