Each time I started my PC, one of the boot-up screens was showing an error (edited):
Since my PC was still working, and I my hard disk was showing more than 465.8GB full, then the second physical drive must be working OK, despite the error message.
Although there is a control panel associated with this screen, there is not an option to fix the problem.
On installing the software, a tray icon immediately noted that one of my drives had an error, and that I should backup data. I ignored this, as the installation required me to restart my PC first. At this stage, the error had not gone.
After restarting, I clicked on the new tray icon to run the Intel(R) Matrix Storage Manager. I pretty icon showed a problem with one of the drives. I select the Advanced Mode view which shows a “tree” listing of my drives. On right clicking on the faulty drive, I selected the option to “Mark drive as normal”. On restarting my machine, the “faulty” drive now appears as normal. Problems solved.