Itunes losing library on external HD -

[T in China]

Machine - 15 inch MBPro 2007 running 3gb of ram
Ran 170 GB Itunes library from a LaCie rugged HD (250GB) for a long time but recent purchase of a Apple TV meant upgrade of disk to WD Passport 500 GB.
All files copied across and working fine. Until the last 24 hours .. All songs podcasts etc show the little exclamation mark next to them ... and "cannot be found" except manually.
I have - verified and repaired the Passport - all ok
Reset and redirected the itunes library in preferences ..
i am now on the painful step of deleting all tunes .. keeping files and readding them to the library ... which takes about 2 hours ...

any advice/insight as to why this happens and workarounds for the future gratefully accepted.

 

[Consultant]

It's not "Itunes losing library"

It's more like: new HD losing library or user didn't transfer library correctly.

 

[T in China]

It's not "Itunes losing library"

It's more like: new HD losing library or user didn't transfer library correctly.

Thanks ..... for not helping at all ..
library has been good for 2 weeks .. until now ..
Does anyone have any constructive advice that doesnt involve killing the database and all my playlists ??