Hey thanks .. this at least put me on the right track. I had in fact eliminated the blank spaces at the end of the file, but I needed to reinsert the CR at the end of the last line. This plugin author now has a new version available at his website. I also advised him that he should update your file ...

Warning: Cannot add header information - headers already sent by (output started at c:\ibserver\www\serendipity\plugins\serendipity_event_ljupdate\serendipity_event_ljupdate.php:196) in c:\ibserver\www\serendipity\serendipity_admin.php on line 7 .. and this warning appears on every page, and add ent...