ReSharper Installer hangs or fails with error (ReSharper 4.x - 8.x)

Possible reason:

• Antivirus software is interfering with the installation process.
• The installer file is corrupted.
• You're installing, uninstalling or upgrading-to-another-version a ReSharper v 5–6 installation in Visual Studio 2010. This might take up to ten minutes before timeout is reached and installer proceeds with a warning.
• Previous version cannot be removed during an upgrade.
• The MSI file is on a network share.
• Some operating system component is corrupted, such as Windows Installer, MSXML, COM, etc.

Solution:

• Turn off antivirus software and run the installer once again.
• Check if the Installer is digitally signed as described in this article.
• If a previous version cannot be removed, try re-downloading an MSI of that exactly version (see the ReSharper archive for past releases). If you got the right version of the file, it should say that the product is already installed on the Welcome page. Choose "Uninstall" on the Welcome page to remove that version.
• Make sure you're running an MSI file from a location which can be accessed by all processes on your system, including Windows Installer services. "Public Documents" might be a good try.
• Run the Installer with logs enabled (command line: "msiexec /i ReSharperSetup.x.y.z.w.msi /l*v C:\resharper_install_log.txt"), and look for Windows Installer errors. Please note, that dialog position/size errors are expected and do not indicate a problem. Many of the typical installer errors caused by the local system configuration can be found in Internet search.