I can't reproduce this behavior.
Do you use the internal or the IE preview ("Options" dialog, page "HTML
preview/export", entry "Preview renderer")?
Is there a "WikidPad_Error.log" file created in the configuration
directory (which can be found by using "Help"->"About" in the menu and
scrolling the info text down to the end)? If so, what is its content (at
least the last few 100 lines)?
Michael