There appears to be another bug crept into the latest version of Illustrator when selecting an object and using the Object > Transform > Move dialogue.
When you change values it commits those values rather than previews them, even if you cancel the operation. Ie. if you type 100mm into the x-coordinate box then change it to 150mm it will move your object 100mm then a further 150mm (250mm in total) rather than honouring the last value and only moving it 150mm.
Illustrator is becoming all but unusable of late.