Got this problem at a client site, had a look at the kb associated with it

How to troubleshoot the “Cannot generate SSPI context” error message
http://support.microsoft.com/kb/811889

and I screamed silently inside as I read it.  As I read on, I thought hang on, what if I change the Native Client access order from TCPIP/Named Pipes the other way round.  Named Pipes first followed by TCP/IP.  What a quick and dirty fix.

Lo and behold it worked.  Oh, and I cheered on the inside.  It’s the only way.