I've been out for the holidays, but in case you are still searching for an answer on this, I recommend verifying the username and password that you have set for the SignUp environment that is being used (Pharos Admin > SignUp > Environments > Network logon & Password fields). Environments are most commonly set at the user group level (the admin may specify a different environment - aka logon credentials - for each user group, but they can be overridden at the computer type level (all patrons logging on a that specific computer type would receive the same profile - commonly used in a children's area where adults might logon on next to their kids or a special ADA computer that is set to large text and/or high contrast for those with impaired vision). Finally, they can be overridden at the script level, but this is very uncommon in my experience.
Hopefully your machines are joined to a domain or you remember the username and passwords. Updating a domain account is as simple as resetting the password in AD, then updating it to match in Pharos. If they are not on the domain, you would need to update your Windows account/password on each machine if the account has expired or you cannot remember the password.
An easy way to test whether or not the password you presented to Pharos will be accepted at the Windows level is to simply disable the SignUp client on the workstation (temporarily, of course). Instructions for doing so can be found here (Disable the SignUp Client temporarily). If Windows rejects the credentials even after SignUp has been disabled and rebooted, then the issue would appear to between Windows and the credentials with which it is provided, as opposed to something being wrong with the way that Pharos is storing or delivering/passing the credentials to the workstation.