Spawning child argument: invalid argument

[Rich Heiberger]

I use that combination all the time.  Probably you need the following three
lines in your .emacs

(setq-default inferior-S+6-program-name
	      "c:/progra~1/Insightful/SPLUS61/cmd/Splus")
(setq-default inferior-Sqpe+6-SHOME-name
	      "c:/progra~1/Insightful/SPLUS61")
(setq-default inferior-Sqpe+6-program-name
	      "c:/progra~1/Insightful/SPLUS61/cmd/Sqpe.exe")

adjust the values for your own setup.  I recommend the 8.3 directory name
"progra~1" rather than the long name with the embedded blank.

You are not seeing a bash problem.  M-x S+6 and M-x Sqpe+6 are the correct
starting functions with bash. 

Rich