I've gone all over the internet with this one, but no avail. Recently, transaction logs overloaded and were moved to another drive and their source updated.  A few days later, some users experienced that they couldn't open attachments in their emails via outlook 03 (.pdf,xls,doc,etc.) Error messages state "the operation failed, an object could not be found.  What is really strange, is that it only has this error coming from some users, others that send attachments they can open.  I'm spining around in circles....any thoughts?

They probably need to clear out their Outlook temp folder, it is odd that it only happens on some and not others but I get you a coke this will work.

First go to the registry and find out where their temp folder, you have to do this since it's hidden.

HKey_Current_User\Software\Microsoft\Office\11.0\Outlook\Security

The entry you're looking for is the OutLookSecureTempFolder, Note the path

There are two solutions however, since this folder gets "full" I recommend just changing the path in the above entry to the users my documents folder and creating a folder called outlook temp, that way you won't have to do this again 

 You could just copy the orginal path in to my computer address bar and clear out the folder however you will just have to do this again in several months.

Export one of the boxes to a pst and see if you can open them there.
Might be corruption in the store.  The files may still exist but the links have gone.

Just to make sure, is this new attachments or existing ones? Can you forward emails and they work etc?

Have tested with new messages also, and same things.  As mentioned before its only from selected people that the attachments wont work all internal.  All external emails containing an attachment is opened without any issues amongst some others.  I'm going to attempt your suggestion.  In regards to the transaction logs, as mentioned, they had recently grown and i moved the mdbdata to another drive, and ran the backup. Could this craziness have anything to do with it, even for messages sent/received days after?

still confused and looking for a reason.

Regards 

Refer back to the posting by JustinC.  Sounds a lot like the "SecureTempFolder" has gone stupid.

Rhyme or reason doesn't seem to fall into it.   I had this one the other day.  Now when you change the name of the folder make sure the full pathname is found.   Also double check and make sure the user in question has full create access on this folder.   You will also have restart the PC (not login logout) to make it work.

And it won't be all computers, it will work in OWA and not Outlook.  You will also find "Save as" doesn't work for the same reason.

 In Outlook 2003 (Don't remember prior versions for this) when you go to open an attachment, it creates a temporary copy in the secure temp folder (Hidden amongst temporary internet files physical location, so you can't NORMALLY view it unless you're a different user or cmd.exe prompt)

What you're viewing is a copy.   If that folder can't be written to for whatever reason that will prevent you from opening attachments in Outlook.

Creating a new one in an alternate location via changing that key will alter things.  I also found when I granted the user full rights to that folder it would autopurge entries from there as well.   I think it's supposed to anyhow but I've found big piles of attachments buried in there that occasionally we need to purge when dealing with the Fax software on SBS 2003.