blank popup menu when clicking menu item with submenu (eVC++ 4,PPC2003 SDK)

Hi All,

I have an MFC application created using Embedded Visual C++ 4 (eVC++ 4) with Pocket PC 2003 SDK.

I created a menu bar using resource editor. The menu has some sub-menus. The menu works very well in normal device using Windows Mobile 6.1 Professional. However, in High-Resolution Devices (e.g. VGA 640x480 pixels, also using WM 6.1 Pro), some menu items went blank (plain white) when i tap on menu item with submenus.

here is the structure of my menu:

HTML Code:

---

menu
- item 1
- menu 1
  + item 2
  + item 3
- menu 2
  + item 4
  + item 5
- menu 3
  + item 6
  + item 7
- menu 4
  + item 8
  + item 9
  + item 10
- separator
- item 11

---

All menus and items are enabled and not ticked. The problem is reproducible with cosistent effects for the same steps. Here are some steps to reproduce the problem:
a) Tap menu > tap menu 1 => menu 2 & menu 3 are now become blank (plain white)
b) Tap menu > tap menu 2 => menu 1, menu 4, separator & item 11 are now become blank (plain white)
c) Tap menu > tap menu 1 => menu 2 & menu 3 are now become blank (plain white) > if we then tap any menu 1/2/3/4, all menu reappear.

Is there any way to solve this problem?
Thank you in advance.

afriza