Registry is not working

I just tried the code myself (Windows 7, .NET 4.0) and initially got a security exception.

I then ran it again 'as administrator' and the registry was duly updated.

However, my anti-virus software (Microsoft Security Essentials) didn't like it at all and wanted to report it.

If you have any AV software installed, I'd try running it again with AV disabled and see if it makes any difference.

The only other thing I can think of is that the OS is redirecting your write to a different key. You could try doing a registry search for notepad.exe to see if anything comes up.

Try calling:

autoStartOnConnKey.Close();