General :: Key Is Not Detected In Xev Neither Showkey -k In Ubuntu 10.04 In A Virtualbox VM?

My question mark key in my keyboard isn't working. ("?"). I've tried to use xev and showkey -k to try to identify at least a keycode and manually use xmodmap to map it. Unfortunately, the keys aren't being detected in neither utilities. I'm using Ubuntu 10.04 in a Virtual Machine (VirtualBox 3.2.4 r62467), and my Kernel is 2.6.32-22-generic. My Host is an Ubuntu 8.04.

When I run xev in my host, I get:

KeyRelease event, serial 30, synthetic
NO, window 0x3600001,
root 0x5d, subw 0x0, time 19346721, (726,722), root:(730,746),
state 0x2010, keycode 211 (keysym 0x2f, slash), same_screen YES,
XKeysymToKeycode returns keycode: 61
XLookupString gives 1 bytes: (2f) "/"
XFilterEvent returns: False

[Code]...

What can this be? It's not a special multimedia key, it's a simple one. I would like to understand what exactly is happening so at least I can try to better debug this issue. If it's detected in my host, why it isn't in my guest?