I have a Japanese Dreamcast VMU, and it works properly with my PAL console.
I noticed, however, that after a while I use it, the card gives me this error message in Japanese, and the only way I found to be able to reuse it is to put it in the controller and pull it out, while the system is on. I tried to translate the message, and the translation is more or less "PERFORM DATA EXCHANGE'.
Do you know how to solve this ''error"?
Thank you so much!

PS: I also take the opportunity to report another problem that I have, which is that when I remove the VMU from the controller or turn off the system, it resets almost every time.