You need permission

I am working on an autoupdater, which, I know, means the first thing I need to test, is making it work to copy files in Windows 7. I run my exe inside the Program Files folder where I want my files copied. To copy the exe, I'm told I need admin rights. Now, I approve of all this new protection stuff, when it works. I try to copy an update, and get a 'you need permission to do this' error. The reason I could not copy it was, I was running it, and needed to close it. If Windows is going to lock me out of the file system, is it too much to ask that it tells me in a meaningful way what the issue is, instead of some generic rubbish ?