Well first thing is to run the tests. Normally if its ram it can be that it will give an option to soak test or just run the test a number of times. If ram is showing up faults it might be time to replace the offending stick in the machine. Far more likely is that there is an ntfs file error and running the disc test with fix file errors will usually sort it. These issues can occur due to a crash while running or a power down due to a power cut etc. Some of the hp machines, thoughothers may do this as well, have a bit of extra software in their bios that can detect some errors and helpfully suggest tests.
I doubt if its a case where a complete reinstall is needed unless you are very unlucky. It might also be wise to check plugs and sockets from the mains, and internally too, as these can be the culprit of crashes or power downs of the hard drive.
Brian