I recently upgraded from Windows Vista Home Premium to Windows 7 Home Premium.  I would have liked to have done a clean install, but I didn’t have the time required to reinstall the many programs I use.  At the beginning of the installation process, the installer performed a compatibility check and found a few programs that might not be compatible with Windows 7.  It recommended that the programs be uninstalled before proceeding with the upgrade.  After that the upgrade went smoothly but, when I tried to run programs under Windows 7, I got an error message advising that Windows couldn’t verify the digital signature of the file.  After doing some research, I discovered that the Norton User Account Control (UAC) should have been uninstalled before upgrading, but Norton UAC wasn’t listed during the compatibility check,  For those not familiar with Norton UAC, one of the features that gave Windows Vista a bad name was Vista’s UAC.  I, like many Vista users, replaced Vista’s default UAC with the free Norton UAC, a more user-friendly and more secure UAC.

I was able solve my problem by booting Windows 7 in Safe mode and uninstalling Norton UAC.  If you are planning to upgrade to Windows 7 and are using Norton UAC, uninstall the program before upgrading.  By the way, the UAC in Windows 7 is much improved over Vista, as are many other features of the OS.