Why does Adobe Illustrator Stop you from moving objects?

When I'm using Illustrator and I click on an object then try to drag it to it to somewhere else on the artboard using the mouse nothing happens. It just won't move unless I use the cursor arrow keys. Why is nothing happening? It's really slowing my workflow down a lot and I need to get it figured out.

All help apreciated thanks

• I'm using Abobe Illustrator CS3 on Snow Leopard
• The mouse is fully working as is the trackpad