Why can't I attach a file to my emails?

I can't attach any files to my emails.. a box appears that says "invalid file specified."?

• I've tried changing the file extention and I've tried closing the file before attaching it... but it wont let me attach any photos or any files at all.. not word documents, tifs or jpegs.. nothing. This is a new problem.. it used to work fine.. any ideas? thanks

• Answer:

  try this............... click tools,internet explorer,security tab,custom level, and scroll down till you come across ("navigate sub-frames across different domains"),click enable, click apply,click ok,and exit your browser. now retry no attach