Installation exited with error 1601 (4327967)

and according to this article:
http://support.microsoft.com/kb/321497

The following steps could be taken to resolve the error:
To resolve this problem, shut down the Windows Installer service and then re-register it. This makes sure that the Windows Installer engine functions properly. To do this, follow these steps:
Click Start, and then click Run.
In the Open box, type msiexec /unreg, and then click OK.
When this process is complete, click Start, and then click Run.
In the Open box, type msiexec /regserver, and then click OK.
When this process is complete, reinstall the update.