There should be a clickable link if you are currently on the SP1 in order for you to update to the latest version.
So, I did a little poking around, and here are some things I found: Microsoft's Resource Monitor, showing that the CPU usage of Microsoft's Security Essentials executable (Ms Mp End.exe) is not using up much CPU (top set of two green arrows); but it is using up most of the throughput of the hard drive (bottom set of two green arrows).
Click to see Full Size Opening the built-into-Windows Resource Monitor, to see what could be keeping Windows so busy, I saw that the executable MSMPENG. It wasn't hogging the CPU in usage, it was constantly accessing the hard drive, but the drive didn't seem to have problems (the response time was ok, etc) - so that indicates that it probably wasn't the hard drive's fault.
Since Ms Mp is part of the Windows Anti-Spyware/Anti-Virus utilities (Windows Defender/Microsoft Security Essentials/etc) I wondered if it was scanning some huge patch/update file that the game was trying to use.
After the 2014-01-18 patch, started failing to start.
It would show "Checking for updates...", then "Updating Agent..", and finally fail saying: "Installation: Something went wrong while trying to launch a program. If it happens again, try restarting your computer." After hitting the close button, there are several processes that continue to run, consuming lots of processor.
If you are one of two million people who played the Diablo 3 beta, you must totally uninstall the beta -- and delete the folders -- before installing the full game.
The folder can be found in the following locations: C:\Documents and Settings\All Users\Application Data\C:\Program Data\/Users/Shared/Once this folder and all other beta files are removed, run the installer.
Users who are currently using Windows Vista as operating system will generally encounter this problem.
In order to install Diablo 3 on a low end computer system using Microsoft Windows Vista, first one must check the service pack version. Right Click on the file and change the Compatibility mode and enable Run in this program in compatilibilty and choose Windows XP (Service Pack 2) 3.
It must be Service Pack 2 SP2 not on SP1 to check your current version, click on the Windows Home button, click on Control Panel, then click on System. Choose Administrator and name it whatever you like. Log in using the new Administrator Account, and pop in the game disc. Run the program by Right Clicking on the executable file and Choose Run as Administrator.
The lowest line the Windows Edition paragraph displays which version you are currently on.