Its strange, indeed...
not sure if this helps, but try add in global.php: @ini_set('max_execution_time', 180);
(doubt it will help though)
If that wont help, try to debug it: in member.php find:$uploaderror = 0;
insert below:print_r($HTTP_POST_FILES);
echo "<br>";
print_r($_FILES);
It should show you something on top of the page after upload.