inno setup.exe fails with Floating point division by zero on Windows XP
===

I have setup an inno setup script that installs my application.  The resulting setup.exe will install properly on windows vista/7 but fails with the division by zero error on windows xp. The inno example scripts work on windows xp so it must be something I am doing.
Can anyone see what I am doing wrong?

    ; Script generated by the Inno Setup Script Wizard.
    #define app_src_path "..\MyApp"
    #define app_exe_path "..\bin"

    #define file_ver GetFileVersion(app_exe_path + "\win32\MyApp.exe")
    #define app_ver Delete(file_ver, 6, 2)

    [Setup]
    AppId={{BBB40316-958C-446B-A08D-311273214AA6}
    AppName=MyApp
    AppVersion={#app_ver}
    UninstallDisplayName=MyApp
    AppPublisher=My Company US
    DefaultDirName={pf}\My Company\MyApp
    DisableDirPage=yes
    DefaultGroupName=My Company
    DisableProgramGroupPage=yes
    #emit 'OutputBaseFilename="MyApp-Setup-' + app_ver + '"'
    #emit 'SetupIconFile="' + app_src_path + '\rc\MyAppIcon.ico"'
    Compression=lzma
    SolidCompression=yes
    ArchitecturesInstallIn64BitMode=x64
    WizardImageFile=ZDS.bmp
    WizardSmallImageFile=ZDSsmall.bmp

    [Languages]
    Name: "english"; MessagesFile: "compiler:Default.isl"

    [Tasks]
    Name: "desktopicon"; Description: "{cm:CreateDesktopIcon}"; GroupDescription: "{cm:AdditionalIcons}"; Flags: unchecked

    [InstallDelete]
    Type: filesandordirs; Name: "{app}\MyApp";

    [Files]
    ; x64 files
    Source: "{#app_exe_path}\x64\MyApp.exe"; DestDir: "{app}"; Flags: ignoreversion; Check: Is64BitInstallMode

    ; win32 files
    Source: "{#app_exe_path}\win32\MyApp.exe"; DestDir: "{app}"; Flags: ignoreversion; Check: not Is64BitInstallMode

    ; platform independent
    Source: "{#app_src_path}\rc\pic1-24.png"; DestDir: "{app}\rc"; Flags: ignoreversion nocompression
    Source: "{#app_src_path}\rc\pic2-24.png"; DestDir: "{app}\rc"; Flags: ignoreversion nocompression
    Source: "{#app_src_path}\rc\pic3-24.png"; DestDir: "{app}\rc"; Flags: ignoreversion nocompression

    [Icons]
    Name: "{group}\MyApp"; Filename: "{app}\MyApp.exe"
    Name: "{commondesktop}\MyApp"; Filename: "{app}\MyApp.exe"; Tasks: desktopicon
    Name: "{group}\{cm:UninstallProgram,MyApp}"; Filename: "{uninstallexe}"

    [Run]
    Filename: "{app}\MyApp.exe"; Description: "{cm:LaunchProgram,MyApp}"; Flags: nowait postinstall skipifsilent
