The Network Address Translator (NAT) was unable to request an operation of the kernel-mode translation module. This may indicate misconfiguration, insufficient resources, or an internal error. The data is the error code.
I get this message occasionally on my Windows XP workstation when I attempt to login to the corporate VPN to soon after I login. This seems to be a timing issue that always (at least on my computer) resolves itself automatically.
There is a KB article from Microsoft if you get this error on Windows 2000, but it doesn't apply to Windows XP.