If you receive the subject message, you are about to exceed the maximum size of the registry. By default, Windows NT calculates the registry size as 25% of the paged pool. The default page pool size is approximately equal to the amount of RAM. The maximum registry size is 152 Meg (80% of the paged pool which is limited to 192 Meg).
The default calculation of paged pool size and registry size is dynamic and is adjusted only as you add or remove RAM.
The settings of two registry values alter the behavior of registry size:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\Memory Management
A value entry of PagedPoolSize as type REG_DWORD sets the paged pool. If this value is missing or set to 0, the system calculates the default page pool as slightly less than the installed RAM but limits it to 192 Meg (0x0C000000). If you change this entry, you must reboot.
A value entry of RegistrySizeLimit as type REG_DWORD directly sets the registry size limit. If the entry is missing, 0x0, or set to 0xFFFFFFFF, the systems calculates the registry size limit as 25% of the paged pool. The valid data range is 0x00040000–0xFFFFFFFE.
You can also set the registry size limit in Control Panel / System / Performance.