User unable to access on default.aspx page in SharePoint 2010

Issue: 

Recently we faced a very strange issue, one of our user was not able to access the site with contribute access. 

Troubleshooting steps: 

First and foremost step is to remove user and add it again. sometimes this option works.

Secondly i tried giving full control to user but still user was not able to access the site. I tried adding user to site collection admins but still no luck.

Then I tried checking the access denied URL , this URL shows which component of the site is denying the access with its GUID. This showed me that it was shared documents which was denying access to user, and there was a webpart on the main page of site which was showing documents from shared folder on default.aspx page. So basically it was a webpart which was causing the access issue.

So the conclusion is either you can remove webpart and check for access or identify with the URL which component is causing access issue.

Hope this information helps.