Odd Reinstall xp pro

I just had a problem with xp pro. After running maint.programs disk cleanup,adaware and avg all still worked well. Then I ran disk defragmenter and all hell broke loose. Nothing worked right dsl not working and slow as could be. Not normal for this comp. After checking everything I could think of I decided to restart. Well after that I couldn't get into windows no how no way. I decided to install xp on another hd D to see if I could save info from hd C. I formatted and did that on drive D xp is now working well on drive D. Now when I check drive C it shows absolutely empty no previous os nothing as if it had also been formatted which it hasn't but is showing in my comp. as C drive but empty. Anyone ever have a similar experience.
Den

 

Ihad the same thing happen using a defragger, boiled down to a bad hard drive.

 

Thanks for the reply tunered. I've had a few hds go bad but they usually give a little warning. This one didn't it's a western digital and only a few months old. Never had defrag kill one by entirely deleting everything before either. I learn something new every day.