Hello HomerJ,
The recommended installation version is to use the web client. I would recommend verifying that everything is uninstalled from QC10 files and if not using the uninstaller available from HP to remove everything. Then try installing using the web based client and do so by first disabling any firewalls or anti-virus and tuning off UAC (as they may cause installation blockage issues), right clickon IE and select the ''run as: administrator'' option (even though you should be an administrator when installing I would still select it) and make sure you have pop-up blocking turned off to allow the installtaion to prompt you as needed for things to be installed, Also make sure you have all the correct prerequisites installed prior to attempting installation (it should prompt you if not installed) as the .net version has increased since QC10 version and I have run into the needed prerequisite holding up installation.

I hope this helps, and if you are still unable to install the client or explorer editions I would suggest opening a case for this issue with your support personnel.

Thanks,
Dan