To resolve QuickBooks Error Code 80004005/80004003, start by ensuring your software is up to date. Check for any available updates and install them. If the error persists, run the QuickBooks Install Diagnostic Tool to identify and fix installation issues. Additionally, ensure that your system's date and time settings are correct. You might also need to re-register your QuickBooks components by running the Reboot.bat file. If none of these steps work, consider repairing your QuickBooks installation through the Control Panel. For further assistance, contacting QuickBooks support or consulting a professional might be necessary.