Outlook Object Model returns new id of public folder items

Hello,

I have a strange behavior when retrieving items from public folders.

I use Java and Comfyj to connect to Outlook. It uses the Outlook
Object Model.
What I have done so far.

1) Connecting to Outlook and retrieving all folder and items in a
folder.
2) Saving the EntryID and StoreID of the items (mails, tasks, etc.)
3) Trying to display an item that is NOT in a public folder works
always!
4) Trying to display an item that IS in a public folder works
sporadic. Displaying the item...

Outlook Object Model returns new id of public folder items