$_SESSION array goes blind when inserting <img src=""> into it

Hello to all people of good will,

On one page I insert into $_SESSION at 'mykey' a value:

<div onclick="parent.load_pic()" id="foto_0"><img alt="image" src=""/
</div>

It comes from a form and is assigned as usual:
$_SESSION['mykey']=$the_above_long_string

And on another page when I start the session and try to read the
$_SESSION array the $_SESSION['mykey'] is empty.

All the other values set elsewhere are right there in $_SESSION array.

I tried addslashes(), htmlentities() but nothing works. To my surprise
it doesn't work in FF, in IE it's ok.

I also discovered that SRC="" attribute is the problem, when I skip it
or misspell it, everything works fine.

Any idea? Thanks in advance,
Joey_33

.