MrsHyde:
The key combination option-x (or y, z or a) will lock to that axis. Try pressing option-x (or appropriate axis) to unlock. If you show the Coordinates Palette, a box will show around the axis designation when locked. Also, pressing the Shift key will lock to the closest axis increment.
You should add a Signature to your Profile (click the Profile button near the top of this page) with your ArchiCAD version and operating system (see mine for an example) for more accurate help in this forum.
David