that's a problem with your computer.
using an online version requires minimum memory of 1 gb Windows or 2 gb Mac.
your issue may be related to too many terminate and stay resident (TSR) apps on your computer. they continue to hog memory even when not in use and that are not needed to prepare the return. or perhaps you are using other apps at the same time like games while preparing your return. it's difficult to give firm recommendations when your OS and computer are unknowns. you can try using the internet to look for a solution. just use the seacrh term - out of memory. be wary of apps that say they can fix your computer problems. some will actually make your computer unusable.
other possibilities include malware