Edit the file /etc/nf, disable autopm, and run pmconfig or reboot.
On SPARC platforms power management may have powered it down. On my SPARC platform, when I don't use my device for an hour or so, and try to use it, it is not working.
(Note: In some cases, the cfgadm disconnect will not make the devices soft hot plugged.) The device node should no longer be listed.
