Actually that's enough information for me. :-) Virtualbox emulates a PS/2 keyboard and tsak has not been very well tested on PS/2 keyboards. I'll need to load up a VM to debug this, so filing a BLOCKER bug report would be a good idea.
I use PS/2 keyboards on my physical systems and I have VMs as well. I can help test.
Might be related: I filed bug report 884. One of the bugs I noticed is even when building tdebase without tsak support (-DBUILD_TSAK=OFF), and in my tdmrc I have UseSAK=false, TDM starts with the dialog to press Ctrl-Alt-Del. That should not happen. I'd like to test further.
We could merge the two bugs into one report.
Darrell