Does a drive I: exist on your system?
My guess is you have a local network and drive I: is on your server. Windows has lost its connection with the server (is it a wireless network by any chance?) or something has stopped on the server.

That message usually means Windows has been lazy and postponed writing some data to a file on the server; now it's decided it had better write the data, perhaps an application is closing and wants to close the file and tidy up, and discovers it can't.

Come to think of it, "I:" by itself isn't really a filename. Heaven knows what Windows thinks it's doing...

Anahata