This can occur when the sswidl.bat files is executing and stops SolarSoft being invoked correctly - it may result from a particular piece of software being installed on the system. I solved the problem by right-clicking the icon for the sswidl.bat file, selecting properties, then the Memory tab. On that tab there is a setting for "initial environment," which I set to 4096 and that solved the problem. This increases the environment space only for the particular session that is run by clicking on the icon, but that is all you need anyway.
Cause unknown - only happens the first time after the tar files have been installed and seems to be site dependant.