[cvsnt] Error communicating with lock server

[IAB]

In some machines (clients), when I update all the project (several 
directories), I obtain the error:

cvs [server aborted]: Error communicating with lock server (send): No such 
file or directory

I search in help and in the Web, but I don't know how correct the error. I 
delete all files and I do a checkout, but when I do a update, again the 
error appears.

TIA
IAB