Help: render objects out of place!!

Hi! can anyone help me? Im new to blender and im trying some tutorials ive found on the web. I have a scene with a chair, a tv and a table, its lit with environment lighting and some other lamps. My problem is that after some renders, i tried to move the objects to different positions but the next time i render the move back to their original locations… ive reseting blender, reseting my pc but its no use… Does anyone know if this is a bug or something? Or if there is anything i can do? Im running blender on a PC with 2 gigs of ram, and a Nvidia 210

The reason is that you have inserted keyframes for that objects probably, go to your keyframes in timeline and press Alt+I that will remove key frames

Thanks a lot! Thats what it was… I cant believe i didnt even consider that! Again, thanks!