I don't know if this error is related on to the Events module, however both modules that I have on my site (a list of upcoming events on the home page that is driven from a primary calendar) error out for certain people.  This is the error that they are seeing:

A critical error has occurred. Please check the Event Viewer for further details.

The event log shows this information:

ModuleId:561
ModuleDefId:170
FriendlyName:Trip Calendar
ModuleControlSource:DesktopModules/Events/Events.ascx
AssemblyVersion:7.3.4
PortalID:0
PortalName:Myrtle Beach Golf Talk
UserID:XXXX
UserName:Rxxxxxxx
ActiveTabID:69
ActiveTabName:Trip Calendar
RawURL:/TripCalendar.aspx
AbsoluteURL:/Default.aspx
AbsoluteURLReferrer:http://www.myrtlebeachgolftalk.com/tabid/119/pmType/ViewMessage/MessageId/4244/Default.aspx
UserAgent:Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.71 Safari/537.36
DefaultDataProvider:DotNetNuke.Data.SqlDataProvider, DotNetNuke
ExceptionGUID:54fbda0f-79f4-45ab-8ed0-6277684b6cc0
InnerException:The time zone ID '(UTC-05:00) Eastern Time (US & Canada)' was not found on the local computer.
FileName:
FileLineNumber:0
FileColumnNumber:0
Method:System.TimeZoneInfo.FindSystemTimeZoneById
StackTrace:
Message:
DotNetNuke.Services.Exceptions.ModuleLoadException: The time zone ID '(UTC-05:00) Eastern Time (US & Canada)' was not found on the local computer. ---> System.TimeZoneNotFoundException: The time zone ID '(UTC-05:00) Eastern Time (US & Canada)' was not found on the local computer. at System.TimeZoneInfo.FindSystemTimeZoneById(String id) at DotNetNuke.Entities.Users.UserProfile.get_PreferredTimeZone() at DotNetNuke.Modules.Events.EventBase.GetUserTimeZoneId() at DotNetNuke.Modules.Events.EventBase.GetDisplayTimeZoneId(EventModuleSettings modSettings, Int32 modPortalid, String userTimeZoneId) at DotNetNuke.Modules.Events.EventBase.GetDisplayTimeZoneId() at DotNetNuke.Modules.Events.EventBase.get_SelectedDate() at DotNetNuke.Modules.Events.EventMonth.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---
Source:

 A similar error is produced from the Events module on the home page.  This does not happen with all users, just a few.  This user also has his time zone set for International Date Line West which seems to be the default for new users for some reason that i have not figured out yet.  The host and portal are not set to that, so that's something else to rack down...

Yes, I have DNN 7.3.4 and Events 6.1.5 (both the latest).

I've also done some more testing and this is what I have found.  My site requires verified users:

 1. Created new user, did not change default time zone from International Date Line West when registered

This user had the error in both of the modules.  Updated the user profile to be Eastern Time.  No more error.

2. Created new user, changed the default time zone to Eastern Time when registering (It's a mandatory field).

This user also had the error.  This time all that i did was go in and click update on the profile, I didn't do anything with the user's time zone.  No error.

3. Created new user, left the default time zone (International Date Line West) when registered.

 This user had the error.  Like #2, I simply went into the profile and clicked Update (didn't change the time zone from International Date Line West) and the errors are gone.

 So it doesn't look like it's the Events module at all, but something with the profile of the user when registered.

Time to look into that...

Roger, good to hear from you, hope all is well!

I pulled down the data from the UserProfiles table, and I see something interesting.

When the user has had their profiles updated (even by clicking the Update button), the Time Zone property changes...

Here are each of the users mentioned above:

1. Eastern Standard Time
2. Dateline Standard Time
3. Dateline Standard Time

And for a fourth user that I have not "updated", I get (UTC-12:00) International Date Line West as the time zone.  And after the user is "updated" (again, just by going in to the User Profile and clicking Update), it has changed to Dateline Standard Time and the errors in the Events modules are gone.

So I have a workaround, however how do I fix it so that the timezone is updated properly upon user registration...