Mysteriously appearing bar in a chart using AP Web Portal

[#1]

An additional bar (green on right) in a bar chart mysteriously appears on occasion.  It skewing the other number in the chart.  This only happens when using a web browser accessing the access point web portal.  When using the desktop version the chart is fine.  I can't trouble shoot it if I can't see it.  I found out that restarting the qlikView server service corrects the problem temporarily.  Days maybe a week later, it happens again.  You help will be greatly appreciated.  QlikView version 10.00.9731.9 SR6 x86