A: Due to additions in Windows Vista regarding User Account Control (UAC) and security scans of programs before they start, in some Vista configurations Windows will run a very lengthy scan of a large program when it is first started up. On some systems this scan is quick (or may not even happen at all), while on other systems it may take 1-2 minutes or even longer to complete. During this time, no dialog or warning box will appear, and in some cases you will not even get a "busy" mouse cursor. This problem is not unique to SR2020 and will happen with any other installer that is composed of a large single file.
The only solution to this is to start the installer (only once) and wait for the initial screen to come up. It is important to note that once SR2020 is installed it no longer requires inserting the original CD, so this delay will only occur during the initial installation.