i think i have a work-around to fix the issue, at least it worked for me.
1) restart WinXP and do not start anything else up
2) restart the VirtualBox installer
3) select 'Repair'
4) After the repair is done, exit the installer ( I didnt see the Reboot option, and i would NOT have chosen it if it did show up ).
5) manually reboot your system ( Start -> Shut Down -> Reboot )
6) a small prayer while your PC reboots (not much else you can be doing during that time anyway)
7) Check VirtualBox settings on the VM you are going to try. I had to redo the Network settings on mine because they were screwed up.
If all looks well, then start your VM.
Hope this helps.