I have 5 users who are experiencing the same issue with Outlook 2007
calendar. Some shared calendars do not update. Other update with no problems.
There is an alert message generated in the "Sync Issues" folder:

13:06:53 Synchronizing server changes in folder 'Z -- Misc'
13:06:53 Downloading from server 'xxxxxx.xxxx.xxx'
13:06:53 Synchronizing server changes in folder '3-25'
13:06:53 Downloading from server 'xxxxxx.xxxx.xxx'
13:06:55 Synchronizing server changes in folder 'Deleted Items'
13:06:55 Downloading from server 'xxxxxx.xxxx.xxx'
13:06:55 Synchronizing server changes in folder 'xxxx xxxx'- Calendar'
13:06:55 Downloading from server 'xxxxxx.xxxx.xxx'
13:07:07 246 item(s) added to offline folder
13:07:07 7 view(s)/form(s) added to offline folder
13:07:08 Error synchronizing folder
13:07:08 [8004011D-526-80040115-0]
13:07:08 Microsoft Exchange is not available. Either there are network
problems or the Exchange computer is down for maintenance.
13:07:08 Microsoft Exchange Information Store
13:07:08 For more information on this failure, click the URL below:
13:07:08
http://www.microsoft.com/support/pro...526-80040115-0


The strange thing is if you shut down and restart Outlook a different
calendar will not update and one that previously did not update will.

Have tried all the usual troubleshooting (rebuild profile, etc) with no
luck. Doesn't seem to be any network problems. We are a small organization
with only one subnet. Problem is not affecting all users, only 5.

User setup:

WinXP SP2
Outlook 2007
Exchange Server 2003