I think I may have figured what is causing the "linkClick" errors showing up in the event log. The new site is replacing a previous site with the same domain name, except there's no /site/ in the new domain path. The new site runs from the webroot. Also, I have moved files around from where they were located on the previous site build. That being the case, I assume the errors are hits from old links people had either book marked or links generated by search engines.

Hopefully as the site ages, the errors will taper off...

There are various tabids involved, but here's one that appears about 30 times (in one day):

UserID:-1
UserName:
ActiveTabID:40
ActiveTabName:Configuration Manager
RawURL:/site/LinkClick.aspx?fileticket=FI_1l1VU_Fk%253d&tabid=40
AbsoluteURL:/site/LinkClick.aspx
AbsoluteURLReferrer:http://www.istmira.com/
UserAgent:Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; FunWebProducts)
DefaultDataProvider:DotNetNuke.Data.SqlDataProvider, DotNetNuke
ExceptionGUID:554ff3e0-d071-46cf-92cd-b693d4ee72cb
InnerException:Unhandled Error:
FileName:
FileLineNumber:0
FileColumnNumber:0
Method:System.Number.StringToNumber
StackTrace:
Message:
System.Exception: Unhandled Error:  ---> System.FormatException: Input string was not in a correct format.
   at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)
   at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)
   at System.Convert.ToInt32(String value)
   at DotNetNuke.Services.FileSystem.FileLinkClickController.GetFileIdFromLinkClick(NameValueCollection queryParams)
   at DotNetNuke.Services.FileSystem.FileServerHandler.ProcessRequest(HttpContext context)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
   --- End of inner exception stack trace ---