Connection Broken after fread()

I'm a new php studient. I have downloaded a webmail example that's have a error. When i attach a file in a newmessage, the browser send me a error, On MSIE i receive "page not found" and on KDE i receive "Connection Broken". This occurs after this command: fread($fd, filesize($path)); I have do make a die() before it so isolate it. My question. Why php stop process and dont send a error message ? How to test file read before a error ocurrs ? Thanks in advance -- Edison Goncalez