Aug 07, 2018 05:59 AM|Deepak Panchal|LINK
You had mentioned that,"there is an image on the home page which links to ReportingServices 'http://alias.com/reports/browse'. When the image button is selected a HTTP 403 error is returned but if the page is refreshed then the
page loads and is accessible."
I suggest you to delete that control and make a test using new control to check whether that specific control has some issue or not.
If new control generate the same error then try to replace it with any HTML control and check whether it helps you to solve the issue or not.
Check the difference in developer window of browser when it is working and when it is not working. It can give some idea about what causing this issue.
Try to make a test on your end and let us know about the results.
We will try to provide further suggestions, If needed.