Guidelines do not appear correctly

Hi, this has happened in Corel 15 and 11 and no idea why but very frustrating.

On correctly setting up the guidelines, they do not appear in the right place!

e.g. When first setting up the page (2080mm wide x 830mm high) I set the guidlines up as I want them and they all appear in the right places. Then, after saving and working on the document, I go to set up some new guidelines ... "0" then appears in the middle of the page?! Is this a fault with Corel or is there something I am doing wrong? I am a long-time, everyday user and this problem crops up from time to time. Ususally I just strat a new page and try again but have just done this 4 times in Corel15 and the guidlines still keep appearing in the wrong place. The correct place for a "0.000" horizontal guidleine is at the bottom of the page!!

Can anyone help?