pcAnywhere and key combos?

Here is my issue – I am using pcAnywhere 8.0 to remotely administer 30 or so public machines. I am using 2 different security softwares, Deep Freeze and Fortres, that both require key combos to turn them off (cntl-alt-shift-f6 and cntl-shift-esc, respectively). I cannot do any virus scanning or anything until these are off. In pcAnywhere, I can log onto these machines and do the usual things, but for some reason those keystrokes do not register on the host machine when I do them on the remote. Why? I can close another program I have with keystrokes and it works fine. Is there any way to get around this??

Thanks

Kate