Assertion NewSize < pool->UserSize failed at ntoskrnl/mm/ppool.c:620

Happening randomly on 2nd stage. VBox AMD-V and NP enabled, 256 MB ram. Contable.

Assertion NewSize < pool->UserSize failed at ntoskrnl/mm/ppool.c:620
Entered debugger on embedded INT3 at 0x0008:0x808ed12e.
kdb:> bt
Eip:
<ntoskrnl.exe:ed12f (lib/rtl/i386/debug_asm.S:33 (DbgBreakPoint@0))>
Frames:
<ntoskrnl.exe:afeed (ntoskrnl/mm/ppool.c:646 (RFreeMerge))>
<ntoskrnl.exe:b002e (ntoskrnl/mm/ppool.c:678 (RPoolReclaim))>
<ntoskrnl.exe:b0ee7 (ntoskrnl/mm/ppool.c:973 (ExFreePagedPool@4))>
<ntoskrnl.exe:91355 (ARM³::EXPOOL:771 (ExFreePoolWithTag@8))>
<ntoskrnl.exe:91aa6 (ARM³::EXPOOL:954 (ExFreePool@4))>
<ntoskrnl.exe:36620 (ntoskrnl/config/cmwraprs.c:68 (CmpFree@8))>
<ntoskrnl.exe:1f670 (ntoskrnl/config/cmalloc.c:295 (CmpFreeDelayItem@4))>
<ntoskrnl.exe:276d0 (ntoskrnl/config/cmdelay.c:248 (CmpDelayDerefKCBWorker@4))>
<ntoskrnl.exe:4ef78 (ntoskrnl/ex/work.c:162 (ExpWorkerThreadEntryPoint@4))>
<ntoskrnl.exe:dc256 (ntoskrnl/ps/thread.c:156 (PspSystemThreadStartup@8))>
<ntoskrnl.exe:53d3 (ntoskrnl/ke/i386/thrdini.c:64 (KiThreadStartup@0))>
<ntoskrnl.exe:dc1f2 (ntoskrnl/ps/thread.c:625 (PsCreateSystemThread@28))>
<00000000>
kdb:>