[SOLVED] Why is Chrome showing a "Please Fill Out this Field" tooltip on empty fields?

Why is Chrome showing a "Please Fill Out this Field" tooltip on empty fields?

I was contacted by my client saying that users complaint saying that some fields now show a tooltip with a message "Please Fill out This Field". I couldn't believe what I heard... but the client is right - using latest Chrome version some fields show a browser tooltip with this message even side by side with my validators!

What's the problem? What am I missing?

Thanks.

EDIT:

The HTML generated by my user control is as follows:

<input name="tbMontante" type="text" maxlength="8" size="10" tbMontante" class="Montantetextfield" 
    FieldName="Montante" 
    Required="True" 
    AllowDecimalValues="True" 
/>

EDIT:

My doctype is as follows:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

Should my browser use HTML 5 to parse it?

Solution