Alias rather than original

[kenglade]

I switched to Apple about seven months ago with no regrets, but had quite a shock today when I went looking for some old (July 2009) image files. I am a semi-professional photographer and I've been careful to save my files to an external disk.

However, when i went to the external disk folder searching for several originals I shot in July I discovered that that the originals were not originals at all but "aliases." When I tried to open the alias I was told they could not be loaded because the originals could not be found.

Can someone please tell me what's going on here? I depend on being able to go back to my originals from time-to-time. How were the aliases created? I must have done it by accident but I am lost as to how.

Does anyone have suggestions on how i can keep the originals with confidence they will be there when I need them other than copying to CD?

This greatly disturbs me and I appreciate your help.