This error means that the password used (as defined in Credentials) is incorrect. This is almost always due to the account having its password changed in Active Directory but not changed in PDQ Inventory (or PDQ Deploy). When a password is changed in Active Directory (or Windows for local credentials) then it needs to also be changed in PDQ Inventory. To update the password go to the Credentials panel under File / Preferences and choose "Edit Credentials".
It is recommended that the accounts used by PDQ Inventory or PDQ Deploy have their password policy set to Never Expire. This is a common practice for accounts that run Windows Services. If having this password policy is not an option for your environment then it is important to remember to update the passwords in PDQ Inventory and PDQ Deploy after changing them in Windows.
Another option is that the password was entered incorrectly in Credentials. Verify that the correct password was entered.