Shoutbox

I have this WD120GB internal EIDE HDD which I bought in 2002. Last year it started to make this loud clicking noise and it was not recognized by Windows, either as an internal or external drive. So i was not able to run any diagnostic software to try to repair sectors as a consequence of not even being recognized. Having nothing to lose, I placed the HDD  in the freezer for a few hours and after letting it warm up I connected it again but the loud clicking noise was still present and unable to be recognized. So instead of trashing it I kept it for months at room temperature. Today out of curiosity I connected the drive externally (using a USB2 enclosure) and guess what? It works flawlessly!. No clicking noise, WinXP recognized it  and I could write/read files to it without any trouble. Question:
- Is this an unusual thing to happen?
- Can I trust this drive? Or given what happened I shouldn't use the drive as a backup?
- I'm running Western Digital's Diagnostic tool to detect/recover any bad sector. Is there anything else I should run to assure everything's fine?
Thanks.