Sometimes when trying to determine the cause of an issue, turning on the debug log can give you additional access to information to help in the investigation. The Salesforce debug log allows you to easily track a large swath of the actions taken by a Salesforce user. Here's what need to do to get started tracking a user's debug log.
1) In Salesforce, go to Setup > Administration Setup > Monitoring > Debug Logs
(NOTE: you'll need to be logged in as a user that has a System Administrator profile)
2) On the Debug Logs page, in the Monitored Users section, click the New button
3) On the Add Users To Debug Logs page, click the magnifying glass icon to find the user you wish to monitor
4) Click the Save button
That's it! The debug log by default will track the next 20 actions taken by that user, so make sure to come back often and click the "Refresh" link for the user to make sure that you fill back up to another 20 logging actions.