Message: The drive containing this and other documents has been disconnected.

Prism Windows shows this alert about disconnected drive when Windows "tells" Prism that a drive has been unmapped/unplugged. There can be several reasons for this.

• A damaged or loose cable.
• Settings within Windows regarding auto-disconnect feature or Group Policy. 

This message originates with Windows, not Prism, and GraphPad cannot help beyond relaying these tips. 

• Check all cables connecting your computer to the drive. 
• Microsoft’s documentation suggests that drive disconnection occurs because the systems can drop idle connections after a specified time-out period (by default, 15 minutes) to prevent wasting server resources on unused sessions. To avoid drive disconnection user should change the default time-out period on the shared network computer:

https://support.microsoft.com/en-us/help/297684/mapped-drive-connection-to-network-share-may-be-lost

• A mapped drive can be disconnected due to Group Policy settings. Since Windows 8, the operating system automatically runs Group Policy updates in the background and disconnects and reconnects the drive to replace it. To avoid it user should make some change in Group Policy object. The easiest way to do it is to run ‘RSOP’ from the command line and change the drive mapping action to ‘Update’ (the required settings are within User Configuration -> Preferences -> Windows Settings -> Drive Maps). This is something for an IT person, not an average scientist, to deal with. 
• Try using a different drive, preferably one that is not networked.