When you try to move your objects, you don't have good control over them and they want to jump around.

This happens when your "Snap" settings are on or set too high. Snap is a feature to help you align objects. 

Chances are likely you're having an issue with Snap, which is a feature to help you align objects. 

Inkscape Snap Tips:

Click the "Enable Snapping" button in the upper right corner of your Inkscape window to turn Snap on and off.

You can also change your Snap settings in Inkscape by going to File > Document Properties > Snap. 

There are additional settings in Preferences > Behavior > Snapping. 

Illustrator Snap Tips:

To turn off Snap in Illustrator, go to View > Snap to grid/guide/point (there are four different options)—select any of those options to turn them on or off.