Thanks for the reply bdbrown, although to be honest I don't quite follow you.
I may not be the most techie of people - I'm a writer, not a coder. But still, I thought this would've been simple - I have another blog where I use a different theme and I don't experience any problems - I just tried it out and it works perfectly... It it were the TinyMCE editor used by WP, why is it only happening to one of the blogs (the Hueman themed) I use.
I think I may have been too quick to point the finger at Hueman for being at fault, but I don't really see what else could be the problem
Thanks again for the reply bdbrown, but I don't know what to do...