In my recent implementation when I changed the date time of the server to and old date the customization and user roles stopped reflecting unless I reset the IIS.
It is because of the caching feature in CRM. IISRESET clears the server cache and everything works fine.
Upon investigating how the CRM2011 cache is managed - there is a Notifications table in the MSCRM_CONFIG database that includes entries that instruct CRM to clear cache items. The Async Server picks these up and notifies the HTTP Worker processes to drop each cache by Key.
The reason my notifications were not getting through was that I had set the server time as an year back. This meant that there were notifications sitting in this table queue that were for an year old. The Async server seems to use the latest date when it first starts to define a time window to query for new notifications. I performed an unsupported DELETE from the MSCRM_CONFIG.dbo.Notification table and all was well again.
Thanks to Develop 1 Limited Blog for the Details