How much ram do you have installed? Which OS? Your link to specs provides no details for your system.
What version of AE are you using down to the last decimal point?
We need to know something about your project. The kind of footage used, the size of the comp you are trying to render, the render settings are all critical information.
I have 3.87GB of usable ram
I'm using windows 7
The project is 1280-720 size, HDTV 720 29.97, 6 seconds long. The footage is a title with effects
You need an absolute minimum of 4 GB of RAM to run AE. That is your biggest problem. Install 8 or 16 GB of RAM and you will see vast improvements.
ok thank you I'll get that sorted! do you think this will solve the error message as well so i can render or could it be down to something else as well?
Ok, so I now have 16GB of ram, just tried to render, and Ive got the same error messages again
Is your version of Windows 7 64-bit or 32-bit?