The message is because the Box-Office is not yet connected to the device driver manager:
This could be because the device driver manager is not started (issue with the firefox package?), or there’s a certificate issue (good version of the pack?) or an anti-virus that is too strict and blocks the communication.
Has there been any changes of the configuration of these PC in the last days ?
Or the operators were just too fast (tried to pay before the connection is finished).
The icon (printer with blue dots) should move to printer without blue dots (and no red cross) after less than one minute.