Can not edit or open function after adding path

I get a really weird error . I can edit -open normally any files. If add a folder in the path then i can not edit open any file. And I get this error.

Any help please?

[per isakson]

"i can not edit open any file" Did you restart Matlab?

Answer 1

[Walter Roberson]

Your path appears to contain an incompatible narginchk.m

What shows up for

which -all narginchk

? It should show up only as a built-in function

Answer 2

[chrichat]

Thanks roberson that was it a toolbox had a nargichk function