There is quite a bit going on that I would not recommend, particularly all the GOTO usage.

But to be more specific to your problem. There are a number of IF ELSE ENDIF statements that are missing an ENDIF.

There are also some SELECT statements that are written incorrectly.

 Code:
$Computer_Name= Left(@WkSta,1)
If $Computer_Name = "w" OR $Computer_Name = "n" OR $Computer_Name = "f"
   GOTO EXECUTE_SCRIPT
Else
   If $Computer_Name = "s"
      GOTO Server
   Else
      GOTO ScriptError
   Endif
Endif

 Code:
If AScan($Server, @WkSta) <> -1
	Call @ldrive + $Path + "\Server\Server.kix"
	GOTO EndPTI
Else
	GoTo ScriptError
Endif

 Code:
$site = LTrim(substr(@LServer,6,3))
$sitecheck = "xxx"
If AScan($Sitecheck,$Site) <> -1
   GOTO SKIP_IP_CHECK
Endif

I'm not sure what you were trying to do in this section, there was a random Case and Endselect, so I just guessed.
 Code:
If InGroup("xxx-Users")
   Call @ldrive + $Path + "\xxx\xxx.kix"
   If @error = 4		; Checks for forced exit of script
      GoTo ScriptError
   Else
      ? "User Is Not A Member of the xxx-User Group"
      GoTo ScriptError
   EndIf
Endif

Also adding a simple assignment statement to function calls will eliminate the 1's and 0's displaying on the console. For example...
 Code:
:ScriptError
$nul = MessageBox($IPMessage, "Kixtart Error",16,5)