If the mount point starts with /cdrom, there's a bug in the way
/etc/mnttab gets updated for HSFS CDroms in Solaris 2.4. Edit
/etc/mnttab and remove the dev= entry for those mountpoints that
give you trouble.
If the mount point name starts with /net/HOSTNAME, where HOSTNAME
is some other host, it's probably Sun bug 1207057. Try patch
102785-01 or later (SunOS 5.4) or 102783-01 or later (SunOS 5.3).
But if HOSTNAME is the current host, it's probably Sun bug 1220440;
unfortunately, this bug is still open as of Jan 2nd 1996.