Strange window opens when I click on calendar

Discontinued products Scheduler for Joomla and WP
#1

I am using WordPress plugin scheduler 2.3.1 http://newberrycheer.com/?page_id=55#date=2011-08-24,mode=agenda and just noticed that when I click on the calendar a popup window appears that has the following…
looks like a hack since poker software shouldn’t be there…
Also the Admin window in the dashboard just gives me flashing yellow bars. Any ideas?

[code]#hesm {position:absolute;overflow:auto;height:0;width:0;},/style>Poker Software
<?xml version='1.0' encoding='utf-8' ?><start_date></start_date><end_date></end_date><rec_type></rec_type><event_pid></event_pid><event_length><![CD
ATA[0]]></event_length><start_date></start_date><end_date></end_date><rec_type></rec_type><event_pid></event_pid><event_length><![
CDATA[0]]></event_length><event id=‘3’

<start_date></start_date><end_date></end_date><rec_type></rec_type><event_pid></event_pid><event_length><![C
DATA[0]]></event_length><event id=‘4’
<start_date></start_date><end_date></end_date><rec_type></rec_type><event_pid></event_pid><event_length><![
CDATA[0]]></event_length><event id=‘5’
<start_date></start_date><end_date></end_date><rec_type></rec_type><event_pid></event_pid><event_length><![CDA
TA[0]]></event_length><start_date></start_date><end_date></end_date><rec_type></rec_type><eve
[/code]

#2

Popup occurs because of broken xml data, which is broken by some output which starts before data generation. ( it seems you have some customization in the wordpress code, or some not very well written plugin, which outputs its code for all requests )