The ArcGIS 10 Desktop File Menu Performance Patch is now available for download on resources.argis.com. The download URL is http://resources.arcgis.com/content/patches-and-service-packs?fa=viewPatch&PID=66&MetaID=1678.
This patch addresses delays encountered when opening the ArcMap 'File' menu when connected to the Internet using some proxy servers. For more details about the issues addressed with this patch, see the following link: Issues Addressed with this Patch.
Esri apologizes for any inconvenience this may have caused you. If you have any issues installing the patch, please contact Esri Support Services.