I will check on this and get back. I think you are getting an error when the installation process reach the "Mailbox Tool". Can you try installing the Mailbox Tool separately?. I believe you can control what to install in the installation process. Can you try installing the Mailbox Tool alone separately from the main installation and let us know?
The installer for ISF v1.1 does have a component selection menu however Mailbox Tool is not available as a choice. I am choosing Demonstration install type but choosing other options generates the same error.
Can you please follow the steps below and let us know if you are successful?
1. Uninstall previous versions of FXLC95000 Mailbox tool if any. Also uninstall previous versions of ISF 1.1.
2. Run ISf1.1 installation.
3. Select "Typical" installation and deselect "Tools" and proceed with installation.
Check if you can complete the installation successfully for ISF 1.1 except Mailbox Tool which is available under Tools section. Please let us know your results.
Also please let us know your PC configuration. Is it 32 bit? Windows 7? Processor?