QuickBooks Error 1603 often indicates a problem with the installation process, usually related to the system configuration or previous software installations. Follow these steps to resolve it:

1. Run the QuickBooks Install Diagnostic Tool: This tool can automatically fix installation issues. Download it from the Intuit website, run it, and restart your computer once the tool has finished its process.

2. Ensure Windows Updates are Current: Outdated Windows systems can cause installation issues. Check for and install any pending Windows updates by going to Settings > Update & Security > Windows Update.

3. Check for Conflicting Software: Antivirus or other security software can interfere with QuickBooks installation. Temporarily disable your antivirus software and firewall, then try the installation again. Remember to re-enable your security software afterward.

4. Perform a Clean Installation of QuickBooks: Uninstall QuickBooks using the Control Panel and delete any remaining QuickBooks folders. Then, reinstall QuickBooks using the latest version of the installer.

5. Repair Microsoft .NET Framework: QuickBooks relies on the .NET Framework, which may be corrupted. Repair it by going to Control Panel > Programs and Features, selecting Microsoft .NET Framework, and choosing 'Repair'.

6. Check Disk Space and Permissions: Ensure there is sufficient disk space on your drive and that you have administrative rights. Lack of disk space or insufficient permissions can hinder the installation process.

If these solutions don't resolve the issue, consider contacting QuickBooks support for further assistance.