found it is a bug of autocomplete microsoft html extension..
for now i disabled autocomplete...
the problem is something like this
If you use an iframe inside a table (iframe in second or
later row (<tr>)), and if you load a file with a form
with 'input=text' fields inside it, the autocomplete for
those fields will be aligned too low.
The amount of pixels between the autocomplete and the
textfield will be the same as the height of the first <tr>
in the parent htmlfile.