The ipldevice file is probably deleted from your /dev directory, or
point to wrong
entry. The '/dev/ipldevice' file is (re)created in boot time 2nd
phase. For additional
information look into /sbin/rc.boot script... The ipldevice entry
type is hardlink. Usually point to /dev/rhdiskN, assuming that boot
device is hdiskN.
Check your system and you should got similar ...
find /dev -links 2 -ls
....
8305 0 crw------- 2 root system 14, 1 Feb 20 2005 /dev/rhdisk0
8305 0 crw------- 2 root system 14, 1 Feb 20 2005 /dev/ipldevice
...
(The first cloumn of the output is the inode number)

So, you can recreate the wrong, or missing ipdevice file.
'bootinfo -b' says the physical boot device name.
For exapmle:
ln -f /dev/rhdisk0 /dev/ipldevice

I hope this will solve your bosboot problem.

Cheers, Zoltan