Virtual Kiosk often gets frozen

After I have started Virtual Kiosk, the first operation I usually do is starting Windows Explorer. It begins to start but often everything gets frozen. To unlock the situation I must press the “Reset” button on the case of the PC.
After the reset, the first time I try again Virtual Kiosk and Windows Explorer the drawback doesn’t happen, however it may happens again the next times I repeat the same two operations.

It seems such drawback doesn’t happen if I first reset the Sandobox, but this is not a solution as everything already existing into Virtual Kiosk gets lost.

This drawback happens with Windows Xp Sp.3, Comodo Antivirus 6.0 and 6.2.