vbox crashes w/ "rc=VERR_NO_MEMORY", but lots of RAM available

[3Dsimulator]

Hi all,
I have a dual processor (Xeon E5-2687W) workstation w/ 384GB RAM currently mounted (physically possible 768GB) running on Ubuntu 22.04.2 LTS kernel 6.5.0-25-lowlatency. Virtualbox version is 6.1.48_Ubuntu r159471.

Problem description: starting a vm can result in a spontaneous crash with the "rc=VERR_NO_MEMORY"-Message. But RAM is free. Only the Linux-System is running (5GB of 384GB). First it seemed that crashes only occurred when assigning more than 105G RAM but then I tried to install a new fresh Win10-VM and this already crashed when trying to enter the windows-Keys.
I tested the physical RAM with memtest -> ok. I assigned 350G of RAM in the Ubuntu Host -> ok.

Hoping desperately for help. Thank you in advance.

extracts of the logfile below (logfile too big)
00:00:01.620443 VirtualBox VM 6.1.48_Ubuntu r159471 linux.amd64 (Sep 16 2023 05:46:21) release log
00:00:01.620447 Log opened 2024-03-08T09:29:21.229227000Z
00:00:01.620448 Build Type: release
00:00:01.620453 OS Product: Linux
00:00:01.620454 OS Release: 6.5.0-25-lowlatency
00:00:01.620456 OS Version: #25.1~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Wed Feb 28 12:15:04 UTC
00:00:01.620515 DMI Product Name: X9DRi-LN4+/X9DR3-LN4+
00:00:01.620533 DMI Product Version: 0123456789
00:00:01.620547 Firmware type: BIOS
00:00:01.620613 Host RAM: 386910MB (377.8GB) total, 379123MB (370.2GB) available
00:00:01.620623 Executable: /usr/lib/virtualbox/VirtualBoxVM
00:00:01.620624 Process ID: 9823
00:00:01.620625 Package type: LINUX_64BITS_GENERIC (OSE)
00:00:01.624792 Installed Extension Packs:
00:00:01.624825 VNC (Version: 6.1.48 r159471; VRDE Module: VBoxVNC)
00:00:01.624835 Oracle VM VirtualBox Extension Pack (Version: 6.1.48 r159471; VRDE Module: VBoxVRDP)
00:00:01.628290 Console: Machine state changed to 'Starting'
00:00:01.628981 Qt version: 5.15.3
00:00:01.629013 X11 Window Manager code: 3
00:00:01.635382 GUI: UIMediumEnumerator: Medium-enumeration finished!
00:00:01.636856 X Server details: vendor: The X. Org Foundation, release: 12101004, protocol version: 11.0, display string: :0
...
00:01:25.565859 GUI: Machine-view #0 focused, reason=3
00:01:40.631108 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:40.631156 91/128: idPage=0x1f0b200 HCPhysGCPhys=0000001f096a3000 rc=VERR_NO_MEMORY
00:01:40.872943 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:40.872994 8/128: idPage=0x1f0b225 HCPhysGCPhys=0000001f096c8000 rc=VERR_NO_MEMORY
00:01:40.873041 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:40.873046 8/128: idPage=0x1f0b29d HCPhysGCPhys=0000001f09740000 rc=VERR_NO_MEMORY
00:01:40.873082 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:40.873087 8/128: idPage=0x1f0b315 HCPhysGCPhys=0000001f097b8000 rc=VERR_NO_MEMORY
00:01:40.873614 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:40.873621 8/128: idPage=0x1f0b38d HCPhysGCPhys=0000001f09030000 rc=VERR_NO_MEMORY
00:01:41.104889 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:41.104933 8/128: idPage=0x1f0b405 HCPhysGCPhys=0000001f090a8000 rc=VERR_NO_MEMORY
00:01:41.104977 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:41.104983 8/128: idPage=0x1f0b47d HCPhysGCPhys=0000001f09158000 rc=VERR_NO_MEMORY
00:01:41.105020 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:41.105024 8/128: idPage=0x1f0b4f5 HCPhysGCPhys=0000001f091d0000 rc=VERR_NO_MEMORY
00:01:41.105056 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:41.105060 8/128: idPage=0x1f0b56d HCPhysGCPhys=0000001f09248000 rc=VERR_NO_MEMORY
00:01:41.105546 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:41.105553 8/128: idPage=0x1f0b5e5 HCPhysGCPhys=0000001f092c0000 rc=VERR_NO_MEMORY
00:01:41.336999 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:41.337066 8/128: idPage=0x1f0b65d HCPhysGCPhys=0000001f093e3000 rc=VERR_NO_MEMORY
00:01:41.337165 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:41.337177 8/128: idPage=0x1f0b6d5 HCPhysGCPhys=0000001f08c5b000 rc=VERR_NO_MEMORY
00:01:41.337263 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:41.337275 8/128: idPage=0x1f0b74d HCPhysGCPhys=0000001f08cd3000 rc=VERR_NO_MEMORY
00:01:41.338138 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:41.338155 8/128: idPage=0x1f0b7c5 HCPhysGCPhys=0000001f08d4b000 rc=VERR_NO_MEMORY
00:01:41.338293 AssertLogRel /build/virtualbox-eW1Ctd/virtualbox-6.1.48-dfsg/src/VBox/VMM/VMMR3/PGMPhys.cpp(6210) int PGMR3PhysAllocateHandyPages(PVM): RT_SUCCESS(rc)
00:01:41.338362 92/128: idPage=0x1f0b83d HCPhysGCPhys=0000001f08dc3000 rc=VERR_NO_MEMORY
00:01:41.338432 Changing the VM state from 'RUNNING' to 'GURU_MEDITATION'
00:01:41.338462 Console: Machine state changed to 'GuruMeditation'