virtualbox.org

I looked for this issue in the user guide and through the forum and google. Found similar but none that referenced the same error.

Host: Windows 7 x64.
VBOX: Version 4.2.16
Guest additions installed previously.

I upgraded this morning to 4.2.16. Got the commone "rollback" error on installation. Modified the MSI file to remove the "MSIProcessDrivers" row. (per a different post on this same site). Thus I was able to successfully install the new version. This same process had worked on a previous upgrade.

Except now, whenever I open an existing virtual machine or try to create a new one, I get the error:
Failed to open a session for the virtual machine XXX.
Failed to load VMMR0.r0
(VERR_LDR_IMPORTED_SYMBOL_NOT_FOUND)

I am attaching the log file of one of the machines I tried to start.

I tried the following to fix it:
Reinstall.
Repair.
Reboot.
Checked for permissions on all relevant files.

Any ideas would be appreciated.

Problem solved.

As stated above, I had been forced to edit the .msi file in order to get the newest version of VBOX installed per post 227792. (I understand from other posts we're not to post links.) One think missing from that is that the drivers don't get properly installed. I also had to right click on vboxdrv.inf and vboxusbmon.inf and select "install". With that and a reboot, it is back to working.