The SIMPSON installer should run without problems. To check that the installation is done successfully, don't try to locate the SIMPSON.exe file and double-click it. It will not work. Instead, you should open the command line (CMD.exe) and type 'simpson' in the window as illustrated above. This lets you verify that simpson works, and you can verify the version number by reading the printed text.
This error typically occurs when you try to upgrade from a previous version of SIMPSON. We are working to solve the problem.
The problem is caused by a problem with the Tcl path. The workaround is to edit the environment variables. This is done by selecting Control Panel > System and Security > System. In the menu on the left select "Advanced system settings", click "Environment variables" and select the entry "TCL_LIBRARY" in the User variables frame. This should only read "C:\Program Files (x86)\SIMPSON\tcl8.6" if you used the default installation path. If you experienced the problem above you probably have several values separated by a semi-colon. Delete the first ones so you are only left with the value above. This should solve your problem.