Since the post was marked [solved] I thought of creating a new post.

Ok. I agree deleting .Xauthority files work, but thats not a good solution. I mean, everytime I have to run any X forwarding application I have to delete the .Xauthority file. Here is my scenario

The applications that I want to run are on Linux Server [NFS] and the client machines [CIFS] that are having problem in locking the .Xauthority files are Macs which share the same domain as that of client solaris machine. i.e. The home directory of particular user on Solaris & the home directory of that user on Mac have same contents.

When I ssh -X from Solaris to the server, everything works fine, no error messages.
When I ssh -X from MACs to the server, I get the following warning messages.

/usr/X/bin/xauth is the path on the server. If I try to break the lock by sudo /usr/X/bin/xauth -b quit, I get the following error
When I ssh -X from any my MacBookPro to the server,

I have checked sshd_config on both the server and the Mac clients, there is nothing that seems wrong, but if you guys have insights then please share

I had a similar problem a while ago, but the error locking the .Xauthority file wouldn't even let me start up x. What I did was drop to command shell, su to root, and chown -r the home directory to myself.
I guess somehow I gave ownership of my home folder to someone else so I couldn't change it at all.
Try the chown idea and let us know if it solves anything.

Thank daweefolk,

But the home directory is already owned by the "user" who logs in.

Somehow I believe this might be due to how NFS and CIFS communicate.

I got this solved. The solution seems very silly and I should had checked long ago.

Solution: I updated the version of X11 app on the client MAC to the latest and it stopped creating those .Xauthority-c files.

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If it helps, with the older version of the X11 apps, I was able to get it done by unchecking the “Enable Authentication” from the preferences of X11 app.