If it will boot to Windows, do the ScanDisk from the drive icon's Properties - Tools tab area and check the box to scan the whole drive and attempt to fix bad sectors.  If it won't boot, post back more system info.

John,

Thanks for the guidance, I followed your instructions and although it took some considerable time and several filesystem checks afterwards everything now appears to be operating fine.

I do have one other query but I'll post that under a different subject.

Thanks for the help!

Leon