There is usually (as Gary said) more to the error than
that. If you see something to the effect of 'unknown
username or bad password', or 'the account is currently
locked out' it usually means that there is a problem with
the identities (accounts) that the PSCOM+ apps are
configured to run under. This is especially so if you
are using a domain account (as opposed to a local one) to
run your PSCOM+ apps.
There are two ways to T-shoot this problem.
1. Unlock the domain account if it is currently locked.
and make sure you know the PW. Open up the 'Component
Services MMC. Right-click each of the COM+ apps that
begin with "MS Project Server" and select "properties".
Click on the 'Identity' tab, and verify the account being
used, and re-enter the PW. Close the property sheet.
You can then either open the right-click menu for each of
the applets & do a 'shut down' followed by a 'start'
command, or just reboot the server.
2. Another reason that the PSCOM ID gets locked out is
documented in KB 312497: "PRB: COM+ Application Under
Domain Account Fails Intermittently". This is because
the 'logon as a batch job' right is not assigned to the
account. The KB has a solution.
I've encountered each of the above problems and used both
solutions to resolve their associated underlying issue
(which was the PSCOM+ account problem)
Make sure you look at the complete error message, as well
as your security logs on the Project Server.
Good Luck,
John