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

Question

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

EDIT: Here is the output from the /LOG

2012-07-14 10:07:50.855   Log opened. (Time zone: UTC-04:00)
2012-07-14 10:07:50.855   Setup version: Inno Setup version 5.5.1 (u)
2012-07-14 10:07:50.855   Original Setup EXE: E:\MyApp-Setup-0.0.0.exe
2012-07-14 10:07:50.855   Setup command line: /SL5="$801DE,623918,137216,E:\MyApp-Setup-0.0.0.exe" /LOG
2012-07-14 10:07:50.855   Windows version: 5.1.2600 SP3  (NT platform: Yes)
2012-07-14 10:07:50.855   64-bit Windows: No
2012-07-14 10:07:50.870   Processor architecture: x86
2012-07-14 10:07:50.870   User privileges: Administrative
2012-07-14 10:07:50.885   Exception message:
2012-07-14 10:07:50.885   Message box (OK):
                          Floating point division by zero.
2012-07-14 10:07:51.654   User chose OK.
2012-07-14 10:07:51.654   Deinitializing Setup.
2012-07-14 10:07:51.654   Log closed.

I don't have a [code] section so I am confused where the MessageBox (OK) message is originating from.

Answer 1

Supplement to Dan's answer that wouldn't fit in a comment...

For the wizard image files, I tried pretty much every possible permutation of color depth and operating system (Windows 7 and Windows XP) using GIMP 2.8 as the image editor. I came up with the following results:

It doesn't matter what color depth you use; 8-bit, 16-bit, 24-bit or 32-bit. Which makes sense when you think about it, because Windows XP does have support for 32-bit icons on the desktop. see edit below

Dan nailed it on the head when he talked about the 'corrupt' header in the bitmap. It turns out that it is not corrupt. By default, GIMP 2.8 saves 'color space information' in the header of the bitmap file. Innosetup or Windows XP (I'm not sure which) doesn't know how to properly interpret this information.

The key is to make sure that this color space information is not saved in the bitmap file. When exporting a bitmap from GIMP 2.8, you have the option to check the 'Do not write color space information' option as shown in the image below.

EDIT 2014-Mar-20

Some updated information: In InnoSetup version 5.5.4 (running and installing on Windows 7 64-bit OS), using the above method with 32-bit images gives a bitmap image is not valid error when the compiled install file is run.

Changing to a 24-bit image, still without the color space information, resolved the issue.