The security validation for this page has timed out. Click Back in your Web browser, refresh the page, and try your operation again

Problem Description
The security validation for this page has timed out" error message when a user submits data to Windows SharePoint Services

Error Message
The security validation for this page has timed out. Click back in your Web browser, refresh the page, and try your operation again.

If you are facing this error message then Microsoft has already published an article on this which is very useful and resolves your issues. Million thanks to Microsoft for publishing this detail information along with root cause.
Thanks to MS

Resolution
http://support.microsoft.com/kb/888828

Content databases contain orphaned items

Problem Description
The SharePoint Health Analyzer detected an error. 

Content databases contain orphaned items.

EXECUTE permission was denied on the object 'proc_putObject', database 'SharePoint_Config', schema 'dbo'

Problem Description
While I was deploying my solution , got an exception as follows

Error MessageEXECUTE permission was denied on the object 'proc_putObject', database 'SharePoint_Config', schema 'dbo'

Reference links for March Public Update for SharePoint 2013

• http://blogs.technet.com/b/stefan_gossner/archive/2013/03/21/march-public-update-for-sharepoint-2013-available-and-mandatory.aspx  

http://blogs.technet.com/b/praveenh/archive/2013/03/19/march-2013-public-update-pu-for-sharepoint-server-2013-is-here.aspx

http://blogs.technet.com/b/mspfe/archive/2013/04/05/sharepoint-2013-march-2013-public-update-required-for-future-cumulative-updates.aspx

http://www.toddklindt.com/blog/Lists/Posts/Post.aspx?ID=398

http://blogs.msdn.com/b/chhopkin/archive/2013/04/04/sharepoint-2013-updates-as-of-april-2013.aspx

http://blogs.msdn.com/b/russmax/archive/2013/04/01/why-sharepoint-2013-cumulative-update-takes-5-hours-to-install.aspx

http://technet.microsoft.com/en-us/sharepoint/jj891062.aspx

http://www.microsoft.com/en-in/download/details.aspx?id=36987

http://support.microsoft.com/kb/2767999

Adding an Email Link in SharePoint site page

There was a requirement raised by one of my user to add Email lnk to the SharePoint site page, I followed below steps to achieve this

Add Content Editor Web Part on the page and in source editor insert following code

<a href="mailto:abc@xyz.com">Email Us</a>

or 

open a site page in SharePoint Designer, select the location where you have to put the link and then insert above code

or 

if you want users to directly open email link on a page when they click on "Email Us / Contact Us" button then assign "OnClick" event to Contact Us button / tab with above code 

<INPUT TYPE="button" VALUE="Email Us" onClick="parent.location='mailto:abc@xyz.com'">

hope this helps