As a consequence of the deficiency in CD40 ligand, the T-lymphocytes in patients with X-linked Hyper IgM (XHIGM) are unable to instruct B-lymphocytes to switch their production of immunoglobulins from IgM to IgG, IgA and IgE.
Windows event logs are also files, but they are commonly locked by Windows (Event Log Service) and it is impossible to open these files on live system. But if the computer is started from another disk or the system drive from the analyzed machine is connected to another computer, you can read event logs as files. The default location of event logs on Vista/2008 and better is C:\Windows\System32\winevt\Logs\.
To view the application log in Event Viewer. Click Start, point to Programs, point to Administrative Tools, and then click Event Viewer. In the console tree, click Application Log. To sort the log alphabetically and quickly locate an entry for an Exchange service, in the details pane, click Source. Double-click a log entry to open an event's properties page. To filter the log to list entries for a specific type of Exchange-related event, from the View menu, click Filter. In Application Log Properties, use the Event source list to select an Exchange-related event source. MSExchangeTransport Events that are recorded when SMTP is used to route messages.