2012-02-11 01:38:55 EET FATAL: could not create shared memory segment: Invalid argument
2012-02-11 01:38:55 EET DETAIL: Failed system call was shmget(key=5432001, size=37978112, 03600).
2012-02-11 01:38:55 EET HINT: This error usually means that PostgreSQL's request for a shared memory segment exceeded your kernel's SHMMAX parameter. You can either reduce the request size or reconfigure the kernel with larger SHMMAX. To reduce the request size (currently 37978112 bytes), reduce PostgreSQL's shared_buffers parameter (currently 4096) and/or its max_connections parameter (currently 104).
If the request size is already small, it's possible that it is less than your kernel's SHMMIN parameter, in which case raising the request size or reconfiguring SHMMIN is called for.
The PostgreSQL documentation contains more information about shared memory configuration.