If 'tmp' is a file that is exactly 25 bytes long, then: 

$fd = fopen('tmp', 'r');
echo "fpos: " . ftell($fd) .
     " eof: " . feof($fd) . "\n";
fread($fd, 25);
echo "fpos: " . ftell($fd) .
     " eof: " . feof($fd) . "\n";
fread($fd, 1);
echo "fpos: " . ftell($fd) .
     " eof: " . feof($fd) . "\n";

results:
                                                        fpos: 0 eof?:
fpos: 25 eof?:
fpos: 25 eof?: 1

This caused one of my scripts to crash since even though
the next fread() didn't die, passing the null it returned
on to an unpack() did.

My current work-around is rather than to use:

while (feof($fd)) {}

I do:

$size = filesize($file);
while (ftell($fd) < $size) {}

However, this obviously won't work on streams that don't come from the local filesystem.

My setup is: (from config.status)

./configure
--with-mysql=/usr/local/mysql
--enable-track-vars
--enable-sysvsem
--enable-sysvshm
--with-gdchart=/usr/local/src/gdchart0.94b --with-gd=/usr/local/src/gd1.5
--prefix=/usr/local
--with-ttf
--enable-magic-quotes
--with-apache=/usr/local/apache

Actually, this isn't exactly correct - I also
compile the CGI version - for which I remove
the apache stuff... and in fact it's the CGI
version that I was using when I noticed the
problem.