EVEN as Amitabh Bachchan makes his long-awaited return to the silver screen with Mrityudaata, an unsavoury controversy over his larger-than-life Rs 64-crore business venture threatens to sour his probable box-office success. Mired in substantial debt for over a year, the Amitabh Bachchan Corporation Ltd (ABCL) is now facing an unprecedented liquidity crunch. Substantial funds are blocked in production and distribution of films; staff salaries are not being paid on time; and public confidence has nosedived. Chief executive Sanjeev Gupta put in his papers earlier this month, to be followed soon, reliable sources say, by M. Suku, vice president-marketing and the other half of the brains trust.