My boss has a very high latency internet connection at home (satellite), and he has problems using outlook with our exchange server, through vpn. He had to delete his .ost and recreate it, and it takes incredibly long to re-download the full mailbox. He wants to take the .ost from his work laptop, after updating it with the latest messages, and then copy it to his home computer and open outlook with that "snapshot" of his mailbox, but it fails to load when we try this, giving an error about it being an old or invalid .ost Does anyone have a foolproof way of doing this?

You can create a Laptop image for his home workstation especially outllook. like backing up through office and restoring it on his home workstation. Also some third party utilities might help .. http://www.recoverytoolbox.com/open_ost_in_outlook.html Also using RDP to office laptop might help.. ( The above are references and never tried before)

His work laptop is not the same kind of computer as his home computer, so an image wouldn't work. We're not trying to recover the data from an ost (like by converting it into a pst), we're trying to circumvent the need to have the ost be created on his home computer by using the one from his work computer. I've seen some discussions that made it seem like this was possible as long as he didn't open outlook and connect to the exchange server in between the last sync to the exchange server from his work laptop (source ost), and connecting to it later through vpn on his home computer after copying the source ost to it. Following that procedure, it still somehow decided that the source ost wasn't "kosher".

Dear, You can copy the .ost file and using in another machine. I have test in my lab environment, it does work. I think the .ost file which you are using might be corrupted. BTW, I would like to suggest you post the thread into the office forum.