That's what I did, that's how I wrote here ( I know NX pass but not SX) I didn't manage to save everything from W98(took hours and sme reboot,shutdown) and then went to buy a new HDD of 300Go.
I restarted to to try to save data without success. I tried Windows 2000 scandisk/chkdsk,windows98 scandisk and also OnTrack FixIt utilities before and it fixed nothing...
My last try was DOS scan disk It found a sector dead on another partition and now my HDD works again as new, I don't understand why another partition gave so many problems, HDD was alsao doing "tac tac tac ..."