When exporting an event, some zip file extractors put the zmEventImagesMaster.html file in a folder with no name. I think this is the case for the built in win7 zipper, and at least 7zip. I found out that this is because the script /usr/share/zoneminder/skins/classic/includes/export_function.php adds a second slash after events. So, 7zip apparently interprets this as if zmEventImagesMaster.html is supposed to be in "events//" rather than in "events/". This creates a situation that will confuse and enrage most police officers I know. Not good.
I fixed it by removing the slash from the first declaration of $monitorPath in function exportEvents in file /usr/share/zoneminder/skins/classic/includes/export_function.php.
becomes this:
I have tested the new exported zip files with winxp default zip extractor, 7zip on windows xp and some extractors on a lubuntu desktop.
If someone tries out this "fix", please try it out with as many deextracors as possible. Some results from a mac for instance, would be great, as I don't have a mac to test this on.