"The specified network password is not correct" is being raised by WMI. The fact that SSCM causes WMI to raise an error, while services.msc fails to raise a WMI error, simply reveals different means of authentication for different objects are being used. Ironically, this is also why BOL recommends SSCM be used, as opposed to services.msc.
A fairly old example of the WMI script with WMI methods that can be used to change SQL Server accounts is documented at http://support.microsoft.com/kb/911839. Given that KB's age, I would not run it on a production box. Even so, attempting to run it could squeeze out further details about what is causing WMI to raise the error (outside of SSCM). It may be worthwhile to search for further documentation about some of the WMI methods within that KB's script (even though there may be precious little additional documentation).
WMI's description of their error (with a few
causes being offered) is at http://technet.microsoft.com/en-us/library/cc959823.aspx. A casual and brief search for that WMI error reveals the SQL Server box's (GMT) time may be way
out of sync with the domain controllers' time. In which case I would expect to see system events with Source: W32Time raising concerns about drifting time/failures to sync. I suspect another cause would be an inability to contact a domain controller for SQL Server (while services.msc might be able to get away with using cached local credentials). I suspect another cause would be a VPN that cannot use/contact SQL Server's domain controller. And I suspect an account that uses a domain alias (which I think is more of a UNIX thing than a Windows thing) would fall flat on its face (when using WMI). And at least one network sniff (at the SQL Server box) may be needed. The goal being to determine what WMI is sending across the wire, to whom its packets are being sent, and what the destination's response was. You may be able to cause services.msc to also
fail, by clearing out cached credentials (but you might be shooting your foot if you did that). The domain admin and the network admin for the SQL Server box may need to pitch in and assist. I recommend trying to avoid changing accounts via services.msc like the Dickens, at very least until after they give up.
I was disappointed to read in a TechNet forum post that some junior and/or wimpy Support person gave up and relied upon services.msc. That is akin to Dogbert Support: "Shut up and reboot the box" and later "Gee, my call metrics are improving"
. Microsoft now uses contract employees for credit card Support cases (the dash in their alias is a dead giveaway, in conjunction with their nearly unintelligible English), and those contractors are paid per Support case. That means the harder a contractor whips their poor employees, the more money they make, and the worse Microsoft Support's reputation is made. Stock is up, though...