Strange .. problem when changing theme

Hi ..

I have a theme that I will use, I was modifying it for days (to integrate it into my website)

but the problem is, when I press “enter” in the posts it doesn’t show up in the post .. the text is crowded ..

here is a picture
https://img710.imageshack.us/img710/2941/nonenter.jpg

but when I change the theme (using any other) , it’s back to normal
https://img151.imageshack.us/img151/3069/entersb.jpg

any ideas ? what can I solve this problem ???

Will be really thankful ..