what damage can javascript do?

I was browsing ma little earlier and netscape bombed out and locked my system up completely (no 3 finger salute function).
When I rebooted norton scandisk told me there was a problem with drive D:'s FAT.

I agreed to let norton sort it out. It then took over an hour to 'fix' the FAT going 2 clusters at a time.
Drive D is now wiped, norton seems to have written junk to the FAT and then read that junk as lost chains.

Is this something to do with Netscape bombing out on the javascript, or is it a problem that's been waiting to be discovered?

When netscape bombs it makes a fairly scary HD grind.

I haven't lost anything vital, but it's left me searching for a lot of install disks that I've lost.

Any ideas?

a java script let loose on a nun secured system can be as nasty as a programmers imagination.

My brother had a hard disk re-formatted on line.