A new guard page for the stack cannot be created

I am getting this error when playing back to back power point slid shows.
Any known reason for this happening?

It doesn’t seem like a Xibo error, more like Windows/.net error.

Did you follow instructions on this page? http://xibo.org.uk/manual/en/media_module_powerpoint.html
It could be caused by .net framework, you could try to reinstall/repair it.

Are there more information displayed when this error occurs?