People have reported that their keyboard seems to "stick" sometimes and that they can free it up by pressing and holding the shift key and then pressing tab a few times. Then, let go of the shift key and tab until you are on the field you want to use.
Shift-Tab is a Windows keyboard shortcut that was designed to reverse the order of the cursor focus through form fields, the reverse of tabbing. This reverses the motion of the curser and should give you an indication of where the curser is.
A less convenient method of freeing the cursor is to close the Reporter and reopen it. In a couple of instances that are similar when people couldn't enter numbers, Num Lock was turned off.