As suggested in other responses the problem is causes by exhaustion of virtual address space. A 32bit linux userspace program is usually limited to 3GB of AS; the remaining 1GB is used by the kernel (rationale: since the top 1GB is kernel fixed mapping it's not necessary to touch the page table when serving syscalls).
RHEL kernels, however, implement the so called 4GB/4GB split where the full 4GB AS is available to userspace processes at cost of a slight runtime overhead (the kernel lives in a separate 4GB virtual AS)