It could be a couple of things,


1: You have hit the insert key by mistake and the manipulator has changed mode. To sort it out just hit the insert key again.

or

2: Your graphics card has issues with Maya, try getting the latest driver from the card manufacturers website.

Hopefully the first one will fix your problem, if not then the second. If neither of them works then unfortunately your graphics card might be incompatible with Maya. Do you have any problems with the manipulator in any of the work views?

Mat.