Could be the first signs of numerous problems, but the first step is generally the same in every case. Make sure your backups are up to date.
If the drive is in the early stages of going out, you'll want backups. If it's a virus or some kind of malware, you'll want backups if it takes the system down with it. If it's filesystem corruption that's gradually progressing, you'll want backups before it makes things irretrievable.
So, get with the making sure your backups are current while others postulate on possible causes.
I turned my PC on today and got the following error
Windows could not start because the follwing file is missing or corrupt: \WINDOWS\SYSTEM32\CONFIG\SYSTEM
You can attempt to repair this file by starting windows setup using the original setup cd-rom...
I turned my pc off and then back on and the system booted as normal - all systems working
I now do not want to shut down my pc in case I get the above error as my windows xp home edition was pre installed in my pc and I do not have the original setup cd.
Any ideas on what to do to stop this error appearing again would be appreciated.