[Jaunty] X won't start after updates

[Josh Holland]

The system in question is 9.04a4 running on VirtualBox from the repos on an Intrepid host.
The installation completed and told me to restart, so I did. Everything works as far as a usplash screen, I see a load of services starting then a login to tty1, which flashes (presumably as X tries to start). The next thing I see is a warning that

"Ubuntu is running in low-graphics mode
Your screen, graphics card, and input device settings could not be detected correctly. you will need to configure them yourself."

I click OK, and get options to "run in low-graphics mode for just this session", "reconfigure graphics", "troubleshoot the error".
Troubleshoot error sends me to another menu. I choose "review startup errors" and get a text editor with :0.log open. The main problems seem to be
"[ 1.190822] (EE) module ABI major version (2) doesn't match the server's version (4)"
"[ 1.190884] (EE) Failed to load module "vboxmouse" (module requirement mismatch, 0)"
"[ 1.190900] (EE) No input driver matching `vboxmouse'"
"[ 1.190915] (EE) config/hal: NewInputDeviceRequest failed (15)"

Looking at Xorg.0.log, these lines seem to be pertinent:
"[ 0.279927] (EE) Failed to load module "vboxvideo" (module requirement mismatch, 0)"
"[ 0.279957] (EE) No drivers available"
"Fatal server error:
no screens found"

Hopefully this is enough to have this fixed. I say this because I had to type the logs in myself.