strange problem with netscape, opera and pageviews

[chotiwallah]

i'm trying to count pageviews on my website. this is part of the code
included in each page:
$query = mysql_query("SELECT * FROM pageviews WHERE datei =
'$datei'");

if(mysql_num_rows($query) != 0)
{
$query = mysql_query("UPDATE pageviews SET hits = hits + 1 WHERE
datei = '$datei'");
}
else
{
$query = mysql_query("INSERT INTO pageviews SET datei = '$datei',
hits = '1'");
}

the "hits" field in the database is incremented every time a page gets
hit. this works fine with IE and mozilla firefox, but NN and opera
count a page twice when you load for the first time. i figure that
somehow a reload is triggered, but i don't know how.

the page contains javascript also, but even without it it counts
twice.

anyone any ideas??

micha