Erratic 64-bit/acceleration recognition

[NotLIable]

I have already checked the user's guide and searched the forum but nobody seems to have the erratic problem I have. I was referred to the forum post for topic 62339, but it does not deal with my "acceleration/64-bit enabled but still can't do 64-bit stuff in VB" problem.

On a Windows 7 box which until a few days ago successfully ran Virtual Box v5.1.22, I am now experiencing erratic behavior when I either try to create a new 64-bit VM or start an existing one. The Speccy program reports that virtualization is "supported, enabled" (verified in BIOS) but VB insists, but not all the time!, that such is not true.

When I try in these cases to start a VM, I see "VT-x/AMD-V hardware acceleration is not available on your system. Your 64-bit guest will fail to detect a 64-bit CPU and will not be able to boot." If I proceed, the kernel reports "This kernel requires an x86-64 CPU, but only detected an i686 CPU. This processor is unsupported in CentOS 7." and stops. The Acceleration tab in the VM Settings menu is grayed out. When I try in these cases to create a new VM, only 32-bit Linux options are offered. Again, VB is complaining that I can only do 32-bit stuff but the BIOS is set to allow 64-bit stuff.

I have completely removed and reinstalled VB software and extension packs and tried the Repair option via the Windows Control Panel. I even re-FLASHed the BIOS chip and re-seated it. A suggestion found online was that a Windows program could be blocking acceleration, but this is too inconsistent. Really at a loss here!

[socratis]

Please go thoroughly through the FAQ: I have a 64bit host, but can't install 64bit guests.

If #1 and #2 are taken care of, #3 is the one you should be looking for. And remember that for #2 cold boot means at least 15 sec switched of. As in take out the power plug.

[BillG]

And if it is a laptop you may need to remove the battery to force it.

However since this problem comes and goes, it seems more likely to be a program on the host machine which grabs hardware virtualization from time to time when it runs. Anti-virus perhaps?

[NotLIable]

It ended up being a faulty BIOS chip, as in the BIOS setup I saw that virtualizaton was enabled, but in Windows, it was disabled. VB now running great, but...

I had backed up via simple copy my .VDI and other files but cannot get my working installation of VB to see all my programs and files. Lots of stuff on this topic out there, but nothing has worked. I'm stuck looking at a virtual disc file with all my work on it and unable thus far to regain access. Any ideas?

[socratis]

Could you please open a new thread with an appropriate title for the new problem you're having? And in this new thread. list the contents of your directory where you have your VM. Did you used snapshots in your VM?

Please do not reply here...