HANA Admin tool error - unable to login

Hello HANA Developer / admin gurus!

I am unable to login to XS Administration Tool (DB version rev.74). 

Using Chrome's Developer tool following error was captured:

http://<hostname>/sap/hana/xs/formLogin/login.xscfunc 500 (Internal Server Error)

Apart from this very generic error, I am unable to find any other traces / error logs.

My user-id has all relevant (and probably more!) xs roles; still unable to find the root cause.

Any help is highly appreciated.

Thanks in advance,

Shaji