sometimes pre is intermittently injected and entire code is displayed

sometimes pre is intermittently injected and entire code is displayed

Some part of the code is visible sometimes instead of webpage.
Even on view page source the same code appears.
On using inspect element i found that a pre tag was injected into the body
with some inline style that cause the code to be visible.
Only some part of the code is fetched.
The displayed content always starts with some random letter and numbers
and then the proper part of code.

these are the two websites :
http://www.funquizcards.com/
http://www.wishafriend.com/
Why is this happening ?
This has started recently. Until recently the sites were working fine.
Refreshing the page fixes the problem.

i have saved the output in a text file.