Using the caret should override the function of a special character and treat it as a literal value:
md c:\R^&S
path %path%;c:\R^&S
As if things aren't cryptic enough
That's what I first thought of, but he already has managed to get the R&S folder in his PATH, somehow.
Escaping the & character with a caret would enable him to add it to the PATH if it were not there already, as would enclosing that folder name in quotes.
His problem arises because, when he tries to add a folder to the PATH from the command line, the command interpreter expands the PATH variable and then borks when it comes to the & character and so will not now add any more folders, at all, to the PATH, although it seems to process it correctly for execution purposes.
Why not just rename the d**n thing R-AND-S? (Not serious)
Anyway, I think I have fixed it. See my other post above.