Since this is a repeat question in my office, I thought I would share the solution with you. Here are two possible scenarios:
1. Draw a polyline with an elevation of 0.00 in location "A". Highlight the polyline and change the elevation to 147.00 and the polyline moves to location "B".
2. Draw a line at any elevation and location "C". Highlight the line and change the elevation of one endpoint to a different elevation and the line moves to location "D".
You might even find that if you try to execute a move command on either the polyline or the line from Step 1 or Step 2, they won't appear to move because the elevation doesn't change.
Do you know what the problem is?
The view has been changed to something other than "Top".
To correct the situation, just type -view at the command prompt and then top to reset the view. You can also find the solution in the dropdown menus at View-3D Views-Top.