Not enough physical memory is available to power on this virtual machine with its configured settings.
It is possible that native applications and/or services have locked down memory which could be preventing the virtual machine from launching. Shutting down unnecessary applications or services may free enough memory to launch this virtual machine.
If you were able to power on this virtual machine on this host computer in the past, try rebooting the host computer. Rebooting may allow you to use slightly more host memory to run virtual machines.