When opening the User folder on another computer it can take some time to open (even 5 minutes or so).
Once you have backed up your files, you can insert the drive back in the notebook and try to perform HP diagnostics on the drive to see if there are any failure id.
Turn off the PC by holding the power button. Turn on PC and continously keep pressing ESC until startup menu appears and then press F2 to enter diagnostics. Try the fast test, or at least the hard drive test.