>>>>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

Did you try on more than 1 PC?