Installation does not finish (hangs at 98%) when installing on Operating System Windows Vista (45931)

While installing and running TOAD on a new Windows Vista PC, several problems are encountered:

a) Several errors occur and installation does not finish (hangs at 98%)

b) After an aborted installation, software cannot be reinstalled(message is: product installed)

c) While running Toad, error 'C:\Program Files\Quest Software\Toad for Oracle\User Files\LexLib.lxl was not found and is needed. Please contact Quest support' appears.

1) Uninstall the partial installation of Toad by selecting the Windows Start Menu | All Programs | Quest Software | Quest Installer | Quest Installer and select to un-install a product.

2) After the un-installation is done, un-check the User Account Control (UAC) option.
This can be done by:
1. Going to Start | Control Panel | User Accounts, in Vista
2. Click on the link "Turn User Accounts Control on or off".
3. Un-click the option and select  OK.
4. Close Control Panel.

3) Install Toad for Oracle again.