Once you start the ECSEL6_WSETUP.EXE program it will download about 200 more files. If the setup program cannot download them then this message will be displayed.
This problem can be caused by virus protection software on the user's machine. The virus protection software can "block" access to enercalc.cachefly.net and then the "file does not exist" error comes up.
The resolution is to add www.enercalc.com, enercalc.net, and www.mykron.com to the trusted sites list in the antivirus program and/or proxy server. Use the ping command at the Windows command prompt to determine the current IP addresses for these URLs if needed - however, the IP address will not help when HTTPS connections are required (like with our online store, or with activation on SEL builds 10.19.** and higher).