Days before filming began, Monroe caught sinusitis; Fox was advised to postpone the production, but the advice was not heeded and filming began on schedule in late April.[10] Monroe was too ill to work for the majority of the next six weeks, but despite confirmations by multiple doctors, the studio tried to pressure her by publicly alleging that she was faking it.[10] On May 19, she took a break from filming to sing "Happy Birthday" on stage at President John F. Kennedy's birthday celebration at Madison Square Garden in New York ten days before his actual birthday.[11] Monroe and Kennedy had mutual friends and although they sometimes had casual sexual encounters, there is no evidence that their relationship was serious.[12] After Monroe returned to LA from New York City, she resumed filming and celebrated her 36th birthday on the set on June 1.[13] She was again absent for several days, which led 20th Century Fox to fire her on June 7 and sue her for breach of contract, demanding $750,000 in damages.[14] She was replaced by Lee Remick, but after co-star Dean Martin refused to make the film with anyone other than Monroe, Fox sued him as well and shut down the production.[15]