You appear to be checking that Login is not already open - which bit of code is actually being run?

Also if login is not open you are opening it in the current area - this is not a good idea as something could already be open there!

Try something like

if !used("login")
  use login in 0 exclusive
endif
select login

>The code seems to work when I run it after opening the project but when running from the executable it fails and gives the message "Cannot update cursor"
>I have tried re-booting and running the executable first but with no success. My intention in the code was to append a blank record to the table and place whatever text is in the text boxes in the appended row.
>Here is the code the runs from my command button:
>
>IF USED ("login") THEN
> SELECT login
>ELSE
> USE C:\login EXCLUSIVE
>ENDIF
>GO TOP
>IF addrec = .T. THEN
> APPEND BLANK
>ENDIF
>REPLACE login.name WITH thisform.loginname.value
>REPLACE login.passw WITH thisform.passw.value
>addrec = .F.
>
>Thanks again!
>Max