title: VirtualBox: VERR_VMX_MSR_VMXON_DISABLED
body: <p>Yesterday I created my first VirtualBox VM (v4.3.28)! I learned that in order to run a 64-bit OS (in my case, Windows 7), I needed to enable Virtual Technology (VT) in my BIOS/UEFI (Intel i7-3770K). I set up my VM to snapshot, and it continued to turn on until after rebooting my physical computer. Now I receive the following error and no longer see 64-bit OS options:</p>
  
  <pre><code>Failed to open a session for the virtual machine &lt;Name of VM&gt;.
  
  VT-x is disabled in the BIOS. (VERR_VMX_MSR_VMXON_DISABLED).
  
  Result Code: E_FAIL (0x80004005)
  Component: Console
  Interface: IConsole {8ab7c520-2442-4b66-8d74-4ff1e195d2b6}
  </code></pre>
  
  <p>I found several posts about this, however the solutions have been to (1) Enable VT via BIOS (as it still is) and (2) Enable a VirtualBox option under Settings>System>Acceleration. Regarding the latter, I am now unable to access the Acceleration tab (the tab is gray). I am not sure how to proceed. Any discussion is greatly appreciated! Thank you.</p>