Exchange/Outlook Sync Errors

I know the folders for sync errors in Outlook have been there forever and I know that the Exchange Mailbox continually syncs with the .ost but I have never really worried too much about the errors. This one lady says she use to get about one sync error a month. Now it appears to be happening daily. Below is one of the errors. What is the general reasons behind sync errors and should I be concerned?





8:27:38 Synchronizer Version 14.0.7151
8:27:38 Synchronizing Mailbox 'Accounting'
8:27:38 Synchronizing Hierarchy
8:27:38 Synchronizing local changes in folder 'Inbox'
8:27:38 Uploading to server 'SBS2008.van-inc.local'
8:27:38     1 item(s) updated in online folder
8:27:38 Downloading from server 'SBS2008.van-inc.local'
8:27:38 Synchronizing server changes in folder 'Cell Phones'
8:27:38 Downloading from server 'SBS2008.van-inc.local'
8:27:38 Error synchronizing folder
8:27:38           [80004005-501-4B9-560]
8:27:38           The client operation failed.
8:27:38           Microsoft Exchange Information Store
8:27:38           For more information on this failure, click the URL below:
8:27:38           http://www.microsoft.com/support/prodredirect/outlook2000_us.asp?err=80004005-501-4b9-560
8:27:38 Synchronizing server changes in folder 'COMPANY CONTACTS'
8:27:38 Downloading from server 'SBS2008.van-inc.local'
8:27:38 Error synchronizing folder
8:27:38           [80004005-501-4B9-560]
8:27:38           The client operation failed.
8:27:38           Microsoft Exchange Information Store
8:27:38           For more information on this failure, click the URL below:
8:27:38           http://www.microsoft.com/support/prodredirect/outlook2000_us.asp?err=80004005-501-4b9-560