Post always go not found but sometimes work fine

Hello there, I’m quite new with wordpress, i just create new blog at http://www.hafizjewel.com , the problem is, my blog sometimes work fine, but sometimes it will become “not found, Sorry, but you are looking for something that isn’t here.”

This really mess me, sometimes when i do reply comment, it will direct me to “not found page”, then i need to click refresh, then it will fine again.. its not happen in frontpage, its also effect me in admin panel..

i try to google the problem, i think this could be a “loop problem”, but i dont know how to solve it..

i use unsupported 2.7 themes, and just changed to new server (I imported database/file) into new server..manual method

please can anybody help me..