What kind of mouse,could be the battery.

 

Do you have a laptop,if so try disableing the touch pad,control panel>hardware>printers>mouse

 

                                                                 OR

 

Control panel>mouse applet>pointer options>uncheck automatically move pointer to default button dialog box.

Yea exactly what tomron said I have a wireless and it does that

when the batteries are low you can also press the button on the

reciever then connect on the mouse so you can get a fresh connection

to the mouse Thats if.... of course you have wireless?? or if its a corded

optical mouse try cleaning the lens or blow it out with air