This alarm becomes active when a process approaches the two gigabyte virtual address space limit imposed by 32 bit Windows.
Note: This alarm is disabled for 64 bit systems.
Processes attempting to exceed this limit on 32 bit Windows may fail catastrophically. Any process that approaches this limit should be closed to free the address space and then restarted if required.
Regardless of the amount of physical memory in your system, 32 bit Windows uses a virtual address space of 4 GB, with 2 GB allocated to user-mode processes (for example, applications) and 2 GB allocated to kernel-mode processes (for example, the operating system and kernel-mode drivers).
NOTE: Some versions of 32 bit Windows Server allow users to change this ratio to 3 GB for user-mode and 1 GB for kernel-mode processes via the /3GB switch in boot.ini.