CRM 2013 - Inconsistent javascript issue crash the web client and user needs to reopen

Question

Hello,
We are using CRM 2013 on premise version and almost 600 users are using it. We have some inconsistent JavaScript issue (following is the log for same) which happens to users in a day or two. When this issue occurs user can not work in system and they have
to open new instance of CRM.
Does anybody knows about this error?
<CrmScriptErrorReport>
  <ReportVersion>1.0</ReportVersion>
  <ScriptErrorDetails>
   <Message>Unable to get property 'location' of undefined or null reference</Message>
   <Line>1</Line>
   <URL>/_static/_common/scripts/main.js?ver=1676323357</URL>
   <PageURL>/main.aspx#313155368</PageURL>
   <Function>anonymous($p0,$p1,$p2){this.$3_3.get_currentIFrame()&&Mscrm.PerformanceTracing.write("Unload",this.$3_3.get_currentIFrame().src);this.$H_3=$p0.toString();this.$26_3();this.$1A_3();this.$1J_3();if($p0.get_isLocalServer())$p0.get_query()["pagemode"]="iframe</Function>
   <CallStack>
    <Function>anonymous($p0,$p1,$p2){this.$3_3.get_currentIFrame()&&Mscrm.PerformanceTracing.write("Unload",this.$3_3.get_currentIFrame().src);this.$H_3=$p0.toString();this.$26_3();this.$1A_3();this.$1J_3();if($p0.get_isLocalServer())$p0.get_query()["pagemode"]="iframe";addPassiveAuthParameters($p0);var$v_0=$p0.toString();if(IsNull($p2))$p2=false;var$v_1=this.$18_3($p0,$p2);if($v_1){if(this.$2z_3()){window.location.reload();return}this.$2d_3();this.$1s_3();Mscrm.PerformanceTracing.write("Navigate",$v_0);!Mscrm.Utilities.isIE()&&this.raiseEvent(Mscrm.ScriptEvents.UpdateTopLocation,null);this.$3_3.get_currentIFrame().contentWindow.location.replace($v_0)}else{this.$10_3();var$v_2=this.get_contentWindow().Sys.Application.findComponent("crmPageManager");if($v_2){!Mscrm.Utilities.isIE()&&$v_2.raiseEvent(Mscrm.ScriptEvents.UpdateTopLocation,null);var$v_3={};$v_3["sourceUri"]=Mscrm.Utilities.getContentUrl(null);$v_2.raiseEvent(Mscrm.ScriptEvents.IFrameReactivated,$v_3)}}window.self.InnerIFrameSrcChangeTimestamp=(newDate).getTime();this.title=$p1;if(window.LOCID_UI_DIR==="RTL"&&$p0.toString().indexOf("PersonalWall")>=0&&window.UseTabletExperience)this.$3_3.get_currentIFrame().style.position="RELATIVE"}</Function>
   </CallStack>
  </ScriptErrorDetails>
  <ClientInformation>
   <BrowserUserAgent>Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.1; WOW64; Trident/6.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; InfoPath.3)</BrowserUserAgent>
   <BrowserLanguage>en-US</BrowserLanguage>
   <SystemLanguage>en-US</SystemLanguage>
   <UserLanguage>en-US</UserLanguage>
   <ScreenResolution>1366x768</ScreenResolution>
   <ClientName>Web</ClientName>
   <ClientTime>2015-04-20T15:41:12</ClientTime>
  </ClientInformation>
  <ServerInformation>
    <OrgLanguage>1033</OrgLanguage>
    <OrgCulture>1033</OrgCulture>
    <UserLanguage>1033</UserLanguage>
    <UserCulture>1033</UserCulture>
    <OrgID>{E8BBA7AE-A552-DE11-B475-001E0B4882E2}</OrgID>
    <UserID>{614837CD-448B-DE11-A5E1-005056970D6C}</UserID>
    <CRMVersion>6.1.2.112</CRMVersion>
  </ServerInformation>
</CrmScriptErrorReport>

Answer 1

Are you on-premise, or on-line? : It's on-premise
Can you reproduce it on-demand, or is it sporadic?: It's sporadic
There is a mention of loading an iFrame in the error, do you have iFrames on the form that generates this error?
It's not on specific forms, so can't identify that. Yes we have iframes on some forms.
Does it happen on any/all entity forms, or specific ones?  Do the entity forms have any custom JavaScript on them?
It's not on specific forms. And yes we have javascript on almost all forms.
Do you have any network problems or slowness in your network? Does the problem happen when the network is busy?
We need to check this on next occurrence.
Do the users that see this error have any unusual add-ins or toolbars in their browser?  This is not for specific user. Its happening for all randomly.
Have you tried other browsers like Chrome or FireFox and do users see the problem there as well?
We need to check only for IE.