That's it -- all my original NEFs, including several weeks' shoots under -processing, were lost (sigh).
I was putting together a new AMD64 3000+ using Gigabyte K8NF-9 MB and 250Gb WD SATA II HD and got flustered after trying for several days to troubleshoot a keyboard problem: kb refused to work after boot-up. It worked perfectly under bios but not after boot-up. Seemed like a bios/software driver bug.
Finally found the kb issue was due to the USB mouse driver. The kb works only if the USB mouse driver is disabled in the bios.
Lesson: burn all NEFs onto backup CDs before processing.
Update:
When my son learnt of my problem, he referred me to a nifty utility tool called GetDataBack for NTFS. I was skeptical at first, as I had not only partitioned and reformatted but also started writing files to the "initialised" HD.
Hey, after trying it out, I was surprised -- gleefully surprised -- that the tool was able to help me recover ALL my lost NEFs and music files ! Obviously it took some hours -- due to some files being overwritten -- but thankfully the files that mattered, the NEFs and music files, were all intact.
Two of the NEFs recovered are shown below. More to follow later.
