Combo Box closes before selection can be made

I have written an application in VB.Net to be run in Windows CE. In it I have a combo box that is populated with numbers representing items that the user will select and use and are then removed from the list. Specifically, a file is maintained with all the numbers that could be in it and a flag is set that tells the program whether a particular number has been used or not. Every time we return to the screen with the combo box on it, it is repopulated.

When we get down to having only 3 selections or less available, the combo box opens when the down arrow is clicked and immediatley closes before a selection can be made.

Any suggestions as to how to correct this problem?

Also, the point at which this problem occurs changes when certain things are changed about the combo box. For example:

The font for the combo box is 9pt currently. If I change it to 12pt, the problem doesn't occur until we get down to only 2 items in the list.

I also moved the box to a different location on the screen and it started occurring with 4 items left.

Any help would be appreciated.



Thanks,

Tromba99