Hi Dave49,
I am sorry to hear that the last steps did not resolve the issue. The next step would be to complete a level 3 uninstall. I have included the steps below for you.
1. Press the Windows key, and the letter R
2. Type %temp%
3. Press Enter, or click OK
4. Open the 7z folder
5. Open the util folder
6. Open the ccc folder
7. Double click the Uninstall_L3
Once the uninstall is complete, you will need to empty the temp folder. To do this just follow the steps,
1. Press the Windows key, and the letter R
2. Type %temp%
3. Press Enter, or click OK
Once you are in the temp folder, you can delete all entries listed. Note that not all entries will be deleted, because some programs are open. For these entries, you can click on skip. Next you will need to empty the trash. After the trash has been emptied, you will need to perform a clean boot. I have included the document 'How to perform a clean boot in Windows'. If your computer does not request it, please restart your computer.
Once the restart has completed, you will need to download, and install the software again. I have included a link to the 'HP Photosmart C6300/6324 All-in-One Printer series Full Feature Software and Driver'.
Please let me know if you are successfully able to install all the software. :)