Found the root cause: XP is limited to 2.5 Gbit/s at network level and it can't handle 10 Gbit/s, thus bluescreening. Showing the option to go to 10 Gbit/s mode should only be displayed to Windows Server 2003 and it's an issue on the driver side as it should never be exposed to XP clients. I'm sorry if the solution isn't very interesting to anyone, but still...