Paper jammed but no paper is jammed.

I have a canon pixma ip1800 printer i bought it to print photos 4x6inch canon glossy photo paper.i use only original ink also.the photos print perfectly all the time,wen i tried printing normal A4 size documentsthe printer wont pull the paper through and it says paper jam,i tried uninstalling and re-installing the drivers and put A4 paper in to print documents from office but it does the same thing,and i even put new ink in but A4 paper wont feed i think it pulls the page a tiny bit tyo the right side then it says paper jammed.but the photos print immediately no problems,so my printer is working but just not for the A4page so wat can i do.