Cannot asign more memory

[Serj-spb]

Using Virtualbox 4.2.6 r82870
Host OS Win7 x64 Ultimate Rus.
Guest OS Win2008R2 x64 Rus.
Hardware i3 2367M; 6Gb Ram.
The problem is that I cannot assign more than 1379Mb RAM. I can set up >=1380 but Guest OS will crash upon booting. Crashing is not at a constant place - sometimes at the logon screen but usually at the boot screen with the running color line.
Tried changing all sorts and combinations of VTx, PAE and chipset options - but it does not affect anything.

[noteirak]

Are you sure you are not assiging more RAM to the VM than what you host has available?

Also, please read minimum information required for assistance

[Serj-spb]

No. I have 6Gb of RAM, and 4 of them are free.
Updated 1 post and attached a log.

[noteirak]

00:00:46.559225 VM: Raising runtime error 'HostMemoryLow' (fFlags=0x2)
00:00:46.559276 AssertLogRel D:\tinderbox\win-4.2\src\VBox\VMM\VMMR3\VMM.cpp(1697) int __cdecl VMMR3EmtRendezvous(struct VM *,unsigned int,int (__cdecl *)(struct VM *,struct VMCPU *,void *),void *): !pVCpu->vmm.s.fInRendezvous
00:00:46.559335 Console: VM runtime error: fatal=false, errorID=HostMemoryLow message="Unable to allocate and lock memory. The virtual machine will be paused. Please close applications to free up memory or close the VM"
00:00:46.559586 Changing the VM state from 'RUNNING' to 'GURU_MEDITATION'.

So your host runs out of free memory and the VM crash - that is confirmed by the log. Virtualbox will require contiguous memory available and cannot use swap or anything of the like, so most likely some of your applications are clustering the RAM or locking it while the VM is running.
AFAIK This tends to happen with antivirus, some google product... but the other mods might give you a more complete list of what to look for.

[Serj-spb]

Thanks for a hint about contiguous memory!
Solved a problem by switching swap file off. According to the taskmgr the free RAM is the same.