As most know, Update Rollup 7 was recently released. There are also some known CRM Outlook Client issues that have surfaced and reported due to the update. Please see KB 976539 for more information about issues associated with this update that may affect the CRM for Microsoft Outlook client.
"Issues may occur in Microsoft Dynamics CRM for Microsoft Office Outlook after you install Update Rollup 7 for Microsoft Dynamics CRM 4.0 or the November 2009 Service Update for Microsoft Dynamics CRM Online"
Donna Edwards 