A knee injury Nicole Kidman suffered on a movie set in Australia has been acting up, leaving the actress with no choice but to leave her latest project, "The Panic Room," just two weeks into shooting, reports Variety. It became quickly evident that she wasn't going to be able to get the job done, the industry paper reports, sending studio executives into a frenzy as they look to re-cast the lead role as quickly as possible. Kidman's exit -- pending final word from the doctors -- heightens the pressure brought to bear on each studio project this year by possibility of a summer work stoppage due to the expiration of the writers and actors guild contracts. It will be a challenge to replace Kidman because most actresses of her caliber are booked for their prestrike slots. There are exceptions, such as Angelina Jolie, who became available when her latest project was shelved.