Sorry to say, but the only reasonable explanation to your dilemma is user error. What you described should have worked, therefore the only conclusion to be drawn is that you didn't actually do exactly what you described. Somewhere along the way, you must not have carefully observed where the file was going to or what you named it. Since it sounds like a simple copy and paste job, you could try again to be sure you're doing it the way you've described it. And files really do not disappear on their own. It's simply not possible. It takes user input to delete a file. It also takes user input to lose a file.
I'm drawing a blank on the acronym AI at the moment. Perhaps someone who knows what that is will have some more insight.
Dear All,
I've been suffering from a similar problem so I decided to revive this thread.
First of all and, believe it or not, I've been using Macs since the Mac 512 and never stopped ever since. I am also and Educational Technologist so although I am not an engineer I have my share of need to understand computers to help others using them for the past 30 years.
I thought this might be in need since I am respectfully and totally disagreeing with toMACsh.
Even if I tend to agree that most of the times and odd problem is explained by some extraordinary user action, there are times where other forces prevail!
Just before sharing my problem with you, let me tell you I recently had an odd problem of Finder misbehaving until eventually it did not startup! Strange enough, Windows on Bootcamp did!
Did all the standard things - safe boot, permission repair, even checked the S.M.A.R.T. status. To no avail. My - now proved - simplistic approach was that if Windows started OK this was not due to a hardaware problem!
Alas, it was. Returning my Macbook Pro to an Apple Authorized Dealer they foud (ready?) that the culprit was a faulty disk cable! I had someone on Apple Support Foruns to explain me that it was indeed possible (my first thought was that I was swindled by the dealer): ir seems Applw uses a much more sophisticated way of controlling the disk and windows did not so thar would explain why the faulty cable could function without a glitch on Bootcam and did no starup on Mac OS. There. There are oddities on the Mac.
Now to my present problem: some times when I uncompress a file with Stuffit Expander, the file does not show up on the folder listing! However if I search for it, it does show up!
So there you have it without user error: a new file not showing up in Finder as it should but after all being there if you search for it!
I am still tying to figure out why (again the SMART status is OK and its a fairly new disk) but I thought of giving you this tip: check with Search for the disappeared filename. Maybe as with me the file is there and is just too shy to show up on first call...
Weird.
Best regards,
-- joão
ps not sure if I'm right but I suspect "AI" to mean Adobe Illustrator