This looks like another post from you. I replied to it concerning if this is a new installation. There is documented for Solaris 7 and below getting this error if you built the system without the proper OEM support.

if the client was installed from an OS Service that did
not include OEM support, the system may not have the proper packages
to run OpenWindows or CDE. The symptom of this problem is an error message similar the following, when attempting to start a windowing system:

/dev/fb: No such file or directory
Graphics Adapter device /dev/fb is of unknown type

The fix is to reload the OS with the proper OEM support -

In order to avoid the above stated problems, the following
recommendations for client configuration must be applied:

1. The easiest solution is to remove the OS Service. Then readd the
OS Service selecting the "Entire Distribution + OEM" as the
cluster type. The Entire Distribution + OEM cluster
will install all the required packages. This is more convenient
than adding individual packages especially if more clients are
going to be added at a later date.