This combination of errors usually occurs because you are trying to run PowerLog Client for the first time from a restricted windows user.
When the Client is first installed it stores it's contacts/users directory files in the installation folder. This folder is not writable for restricted users and read/write access is required for Jet Databases to operate.
The solution is to log in to Windows as an administrator, run PowerLog and then re-point the Directory to a location that is accessible to all. This option is in the Settings menu > Directory Settings.
You should be doing this anyway in a multi-user environment since the whole point of the Directory is to be a shared information store. A share on the PowerLog Capture machine would seem like the ideal place.