Dissapeared files in my inbox

Hi,

I sort my ongoing corr in subfiles in my inbox.

When a clientcase is closed i rightclick and save the whole case in "Convert to PDF" which i then save on a extern harddisc.

I was doing this, one at a time when I saw that around 12-16 subfiles (Ongoing projects) where gone.....

Where could they be?

Pls. help