That is the entire error message. I am checking with the hosting company to see if this is something on the server side. I had built another site with the KTML Interakt upload WYSIWIG a long time ago and remember running into a similar problem and there was some setting on the server that prevented a temp directory from being created. It seemed that the image file is uploaded to a temp folder and then transferred to the one that you identify.
KTML not being supported by Coldfusion is the reason I am switching to iRite.