NSIS Help please.

First you have an error here -

System::Call 'kernel32::CreateMutexA(i 0, i 0, t "SkinnerPortable"2) i .r1 ?e'

that should probably be -

System::Call 'kernel32::CreateMutexA(i 0, i 0, t "SkinnerPortable2") i .r1 ?e'

instead.

Second, you need to include StrRep.nsh as well when using ReplaceInFile. Here it is in case you don't have it -

; StrReplace
; Replaces all ocurrences of a given needle within a haystack with another string
; Written by dandaman32
 
Var STR_REPLACE_VAR_0
Var STR_REPLACE_VAR_1
Var STR_REPLACE_VAR_2
Var STR_REPLACE_VAR_3
Var STR_REPLACE_VAR_4
Var STR_REPLACE_VAR_5
Var STR_REPLACE_VAR_6
Var STR_REPLACE_VAR_7
Var STR_REPLACE_VAR_8
 
Function StrReplace
  Exch $STR_REPLACE_VAR_2
  Exch 1
  Exch $STR_REPLACE_VAR_1
  Exch 2
  Exch $STR_REPLACE_VAR_0
    StrCpy $STR_REPLACE_VAR_3 -1
    StrLen $STR_REPLACE_VAR_4 $STR_REPLACE_VAR_1
    StrLen $STR_REPLACE_VAR_6 $STR_REPLACE_VAR_0
    loop:
      IntOp $STR_REPLACE_VAR_3 $STR_REPLACE_VAR_3 + 1
      StrCpy $STR_REPLACE_VAR_5 $STR_REPLACE_VAR_0 $STR_REPLACE_VAR_4 $STR_REPLACE_VAR_3
      StrCmp $STR_REPLACE_VAR_5 $STR_REPLACE_VAR_1 found
      StrCmp $STR_REPLACE_VAR_3 $STR_REPLACE_VAR_6 done
      Goto loop
    found:
      StrCpy $STR_REPLACE_VAR_5 $STR_REPLACE_VAR_0 $STR_REPLACE_VAR_3
      IntOp $STR_REPLACE_VAR_8 $STR_REPLACE_VAR_3 + $STR_REPLACE_VAR_4
      StrCpy $STR_REPLACE_VAR_7 $STR_REPLACE_VAR_0 "" $STR_REPLACE_VAR_8
      StrCpy $STR_REPLACE_VAR_0 $STR_REPLACE_VAR_5$STR_REPLACE_VAR_2$STR_REPLACE_VAR_7
      StrLen $STR_REPLACE_VAR_6 $STR_REPLACE_VAR_0
      Goto loop
    done:
  Pop $STR_REPLACE_VAR_1 ; Prevent "invalid opcode" errors and keep the
  Pop $STR_REPLACE_VAR_1 ; stack as it was before the function was called
  Exch $STR_REPLACE_VAR_0
FunctionEnd
 
!macro _strReplaceConstructor OUT NEEDLE NEEDLE2 HAYSTACK
  Push "${HAYSTACK}"
  Push "${NEEDLE}"
  Push "${NEEDLE2}"
  Call StrReplace
  Pop "${OUT}"
!macroend
 
!define StrReplace '!insertmacro "_strReplaceConstructor"'