Tiari, if scandisk helped that much, then it's a sign that the disk is due for replacement...
If you're getting that many bad sectors, then there's a serious problem with the disk, and it won't get better, only worse, and probably exponentailly...

Get a new disk as soon as you can and copy the data onto the new one.

You'll curse yourself if you don't! You can always keep the old disk and use it for "temporary" stuff, until it finally gives up the ghost..:-)

Cheers,
Diolma