Edit control not responding to Delete key

I have a form with a Sheridan SSIndexTab control and several text boxes on the various tabs. At run time when the focus is on any of the text boxes, all keys work as usual EXCEPT the delete key, which does nothing. If I set a keydown event for the text box, I get nothing when delete key is pressed (event does not fire). Delete key on keyboard is fine.

Using SPY++, I can see the VK_DELETE messages going to the edit control.

I also notice that the style bits for the edit control include WS_MAXIMIZEBOX! When I create other forms (with working text boxes!) I do not see that style bit being set! Alas, this bit is not able to be set at runtime by SetWindowLong so I cannot easily duplicate the behavior.

No forms have KeyPreview set to true. I am not using any Keypress or KeyDown event handlers. Vb6, sp3 NT4 Workstation SP 4.

Any one seen this before? I am completely stumped...

Wade