Combo Boxes / Navigation

Dear Sir,
I have recently added a search function to one of my existing databases using a combo box, this simply uses a persons name to search through the existing table (I used the wizard to set this up).

The search box (combo box) is positioned at the top of the form. When I type the persons name into the box and press enter it finds the record perfectly. However, if I use the tab key to move from the combo box to the next field it moves it to the next record. For example:

1) I type Smith in the combo box and the record appears for Mr Smith (record number 340);

2) I use the tab key to move to the next field and it changes to record 341.

Can you tell me how to stop the record changing when I press the tab key please.

Kind regards,

Darren.