A solid fan-proposed concept for Star Trek 3
From the full plot
On the Enterprise, the unknown probe has been brought aboard and is being studied by Chekov and a team of engineers. They're perplexed by the technology as it is both incredibly advanced and apparently very old. Switching scan modes on his tricorder, Chekov triggers the probe's reactivation protocol and it snaps to life, killing several crew members in a matter of moments. Chekov is able to narrowly escape death but the probe, now having sprouted mechanical legs, rips open the door and escapes into the corridor.
As the probe tears through the Enterprise, crew members are scrambling to get out of its way. With razor sharp manipulator arms, it cuts through bulkheads (and unfortunate crewmen) like paper. Security teams are unable to stop it from reaching its goal: the Enterprise computer core. With the probe interfacing with the core and now protected by a forcefield, the Enterprise leaves orbit and jumps into warp for parts unknown.