Hi All,
Thanks for your support, the issue is resolved. It was not dashboard neither the Webi report which had issues. Accidentally, the issue is resolved 
.
I thought that this might have been a cookie issue so I tried one of my colleagues machine and it worked fine. So I thought of clearing caches and cookies (Which looks like the primary issue). But the clear cache option on the developer screen did something which made none of the browsers workable 
. So I had to reset my entire profile and post a reboot the report opens up without any issue.
Yep, so the reason was cookies / cache. But I will never use the clear cache option from the developer screen 
.
Thanks