You did not provide any info about your system, your project, your footage, your render settings etc., which makes your whole comment utterly useless....
I have AE 9.0.3, using a windows Intel Core i7-2600 Processor (8M Cache, 3.40 GHz) 4GB RAM.
It a very simple project, with version 9.0.2 to and are already' succeeded in renderind and after the upgrade to 9.0.3 fails more to do, after a good start and fast after a while begins to slow down until total blockade.
Sorry but I do not speak English and it's difficult to explain. Do you understand Italian?
The project I usually rendered above is an file.mov of 29451 kb.
There are common causes to many problems in AE. Here is a list of them:
Are you trying to use multiprocessing, also called "render multiple frames simultaneously"? Turn it off: you don't have enough memory to make it work.
Are you using Open GL to make rendering faster? Turn it off: Open GL does not work well for rendering.
Are you using footage from a DSLR, HDV camera, GoPro camera, or Sony XD camera? Many cameras record video using an encoding technique called long-gop, and AE 9 can't use it. You should convert it to a lossless codec like Quicktime's Animation or PNG codecs.