Upgraded to Wordpress 3 now I can't insert images!

I've just auto upgraded to wordpress 3 via my dashboard and now I have a problem with images.

Basically if I try to upload an image I can go through the upload process but can no longer insert images into posts as when I press insert into post I just get a blank screen and the only way I can get back to the insert post is with the back browser button, but there's no sign of the uploaded image.

Apologies if this isn't well explained but it's quite frustrating and I'm desperately looking for a fix!