Events Get Lost (from OnBlur To OnClick)

*The Situation*
A traditional situation where HTML form inputs are checked...

(if simplified then it would look something like this)

<form onSubmit="return checkWholeForm(this)">
<!-- other inputs -->
<input type="text" name="anInput" onBlur="dataCheck(this, ...)" />
<span id="error_anInput"></span>
<!-- other inputs -->
<input type="submit" name="btnSubmit" />
</form>

dataCheck validates the inputs value and if something is wrong, then..
document.getElementById('error_anInput').innerHTML = 'Error!'
or if data is valid then the content of span is removed.

The checkWholeForm function iterates through all elements on the form
and triggers onblur() for each input... leading to executing function
dataCheck (and so changing innerHTML of some specific span elements if
needed).

*The Problem*
If I have entered incorrect data to an input and hit the submit button
with my mouse (causing the onBlur event to be triggered just right
before onSubmit) then *occasionally* for some fields the onSubmit event
is not triggered because the onClick event is not triggered. :S

As there are actually quite many complex functions (tested and these
seem OK afaik) that are doing the checks then dowes anyboudy have a clue
what type of code might break this. I thought at first that setting
innerHTML to some value during onBlur disables all waiting events but as
this is happening occasionally (on some machines) I'm in doubt...

any ideas what to check? double declaration of function/variable names?
Not deleting some object after usage? ... anything?

Waiting for any ideas...

PS. http://eix.lap.ee/test/portali_js.html in the example *occasionally*
third field generates the error - remove any content from the field
and stright hit the submit (*with mouse* - to create onBlur and onClick
at the same time).