free/busy folder errror

hi all, first of all can someone kindly explain the free/busy folder to me? Im not sure what it is . .

I ask this as I have found the following error in the event log of one of my users machines . .they say outlook crashes regularly. The user is using outlook 2010 from a terminal server if that helps.

Thanks

Log Name:      Application
Source:        Outlook
Date:          04/12/2012 14:14:38
Event ID:      25
Task Category: None
Level:         Warning
Keywords:      Classic
User:          N/A
Computer:      MAN-TS.ojassociates.local
Description:
Cannot load personal free/busy data. Network problems are preventing connection to Microsoft Exchange.