Windows Live Mail Calendar event create/drag and drop problem

I use the offline version of the calendar in WL Essentials, and in week view when I try to click on a block to create an event or move an event in some cases it want to create wrongly. For ex. you click on the block of 12.00-12.30 it always opens the window with the correct block hours, same when you click on the vlock of 13.00-13.30 OR 13.30-14.00... BUT when you try to click on the block of 12.30-13.00 for example, it always higlights the previous block and when double clicking on it the events start is automatically appears from 12.29-12.59...same happens with 10.00-10.30 etc....thats really annoying and going over years now through different OP systems, platforms, laptop and desktop...