Is/was your Windows XP 32-bit? (I assume yes) Is your Windows 7 64-bit? (I assume yes)
The "Program Files" folder on a 64-bit Windows system is for 64-bit applications. The "Program Files (x86)" directory is for 32-bit applications.
Windows 7 also has "UAC" (User Access Control), which is a security feature designed to make it harder for malware/viruses to infect your computer. This imposes restrictions on what should be going on in the Program Files directories, as well as the Windows system directories. So depending on what your executable files are doing, they may be denied the ability to write in the directory, so if you were expecting that to happen, you are out of luck -- and that would be consistent with it working in other directories.
