Puzzling!
With a fex specified to Projects on Dev Studio I can't run the fex due to above error with the right-click run button or the running man, however if I right click then edit text then click running man it will execute.
Anybody had the same problem
TIA

I've had similar problems due to case sensitivity (something saved in upper case, but Dev Studio expects lower case), but then it is pointing to a Unix hub.

The very obvious. Does your fex name contain a space or other none standard character. That would cause the problem. Current versions of dev studio allow you to use spaces even though they are not supported. (7.1 does not)