HI lucy2960:
Thank you for your query. I am happy to be of assistance!
I understand that your computer is running slow and the HP Support Assistant is finding the updates but not able to install them. Here is a link to documentation on "Downloading or Updating Software and Drivers for HP Computers" click here. As the HP Support Assistant does not appear to be working correctly I would suggest uninstalling it and download and reinstall. Hopefully that will resolve 1 issue. Here is a link to the HP Support Assistant click here. Please let me know how it turns out.