If all other solutions fail, is it possible that the MSI 1603 error indicates a problem with the operating system itself, and what steps can be taken in such a scenario?

Yes, if all other solutions fail, it's possible the operating system itself has underlying issues. In this case, consider the following: 1. **System File Checker (SFC):** Run `sfc /scannow` in an elevated command prompt (run as administrator) to scan for and repair corrupted system files. 2. **Deployment Image Servicing and Management (DISM):** If SFC doesn't fix the issue, run `DISM /Online /Cleanup-Image /RestoreHealth` in an elevated command prompt to repair the Windows image. 3. **In-place Upgrade/Repair Install:** Perform an in-place upgrade (repair install) using the Windows installation media. This reinstalls Windows while keeping your files and applications. 4. **Clean Install:** As a last resort, consider a clean install of Windows, which will erase all data on your system drive. Back up important data before proceeding.