>>>My guess it's related to Windows version and user access rights. For troubleshooting, try to run application as admin and see if it fixes the problem.
>>
>>I've tried to run myapp.exe "run as administrator" still same :(
>
>As I said, I don't think it's Excel 2007 problem. I have Excel 2007 on my PC with WinXP SP3 and I have no problem executing your code.

May be this is w7 bug :( or corrupted installation set