Why can't i upload an profile image on facebook?

I click on browse to get an image, i click on the image, tick the terms and conditions box and then press upload and the bit where it says where i browsed it from just disappeares and doesnt do anything!! Why?!?!?! I uploaded an image this afternoon and it worked perfectly well.





Would anyone know why?!





Please help.
Why can't i upload an profile image on facebook?
The uploading thingie accept only JPG files and Bitmap files. The other 1 type of file it accepts is listed in brackets below the box where you put the location of your picture. The pictures that do not upload are some other files other than the 3 Facebook allows.