Most likely, you are working with resources which don't have enough permission in Window 7. For example, you cannot create or modify any files beyond special directories in the "Users" directory. To start, try to run the application as administrator. It's not enough to log in as administrator, you also need to run the application with elevated privileges. Here you will find the options you can use:
http://www.sevenforums.com/tutorials/11841-run-administrator.html[
^].
If it does not help, use XP compatibility mode, see
http://windows.microsoft.com/en-US/windows7/products/features/windows-xp-mode[
^].
After all, write an application which is a good Windows 7 citizen. See the guidance:
http://msdn.microsoft.com/en-us/library/dd371778%28VS.85%29.aspx[
^].
—SA