Pinned topic WDzv601 will not install

I have downloaded the eAssembly files to re install WDz 6.0.1 on my machine. Installation fails with the following message:

"Cannot load the referenced location for b_wdz601_update"

I have downloaded the eAssembly for disk 4 twice incase the b_wdz601_update.zip was corrupted. Still same problem.

I am installing WDz v6.0.1 ontop of WDz v6.0. Does anyone have any ideas what the problem could be?

Here is the actual log entry for the error message:

(Nov 28, 2006 2:04:51 PM), Install, com.installshield.wizard.platform.win32.Win32ProductServiceImpl, msg1, installing CDI Install Archive (b_wdz601_update)
(Nov 28, 2006 2:04:51 PM), Install, com.ibm.rational.cdi.archive.CDIInstallArchive, err, An error occurred and product installation failed. Look at the log file C:\IBM\WDz601\logs\wdz_install.log for details.
(Nov 28, 2006 2:04:51 PM), Install, com.ibm.rational.cdi.archive.CDIInstallArchive, err, ProductException: (error code = 601; message="err"; additional data = b_wdz601_update:com.ibm.rational.cdi.exception.CDIException: Cannot load the referenced location for b_wdz601_update.)
STACK_TRACE: 12
ProductException: (error code = 601; message="err"; additional data = b_wdz601_update:com.ibm.rational.cdi.exception.CDIException: Cannot load the referenced location for b_wdz601_update.)
at com.ibm.rational.cdi.archive.CDIInstallArchive.install(CDIInstallArchive.java:390)
at com.installshield.product.service.product.PureJavaProductServiceImpl.installProductAction(PureJavaProductServiceImpl.java:1916)
at com.installshield.product.service.product.PureJavaProductServiceImpl$InstallProduct.getResultForProductAction(PureJavaProductServiceImpl.java:5195)
at com.installshield.product.service.product.InstallableObjectVisitor.visitComponent(InstallableObjectVisitor.java:369)
at com.installshield.product.service.product.InstallableObjectVisitor.visitInstallableComponents(InstallableObjectVisitor.java:333)
at com.installshield.product.service.product.InstallableObjectVisitor.visitProductBeans(InstallableObjectVisitor.java:133)
at com.installshield.product.service.product.PureJavaProductServiceImpl$InstallProduct.install(PureJavaProductServiceImpl.java:4563)
at com.installshield.product.service.product.PureJavaProductServiceImpl$Installer.execute(PureJavaProductServiceImpl.java:3758)
at com.installshield.wizard.service.AsynchronousOperation.run(AsynchronousOperation.java:41)
at java.lang.Thread.run(Thread.java:567)