After Effects keeps crashing today for some reason..says I am out of application memory....has happened 3 times in the last 20 mins and I haven't had this issue before. Any idea what could be causing this issue?

I'm on an iMac
32 GB 1600 MHz DDR3
3.5 GHz Intel Core i7
NVIDIA GeForce GTX 780M 4096 MB

I'm on an iMac
32 GB 1600 MHz DDR3
3.5 GHz Intel Core i7
NVIDIA GeForce GTX 780M 4096 MB