I get an error message about a failed registration of a .dll file while installing Nokia PC Suite.

You have probably already installed Nokia PC Suite on your computer and you are trying to install an older PC Suite version. Try to uninstall the following Nokia PC Suite components manually before installing Nokia PC Suite again:1) Nokia PC Connectivity Solution2) Nokia Connectivity Cable Driver3) Nokia PC SuiteAfter uninstalling, reboot your PC.

The components listed above can be uninstalled from Start > Settings > Control Panel > Add or Remove Programs