For HP you will need to use SAM to make changes to the kernel...that is what you are looking at. SU to root and call up sam. Take a look at all of the parameters that oracle needs to run (like SHMMAX, NPROC, NFILE, etc.) and make sure that they are more than what Oracle suggests in the installation guide.
But, like jovery said, try it with the shared_pool_size and db_block_buffers a little smaller first just to make sure that that is what is happening - that there is not enought memory allocated for oracle to start. Other possible things may be corrupted memory segments, zombie processes chewing up the allocated memory, etc. If you are not sure about these other things that are OS related then check with the sys admin on that. Also make sure that you have enough swap too.