are you running win2k? guess so, because this is a typical w2k bug of tasks.dll when hooked in a box.
hooking the tasks.box into another box should solve this, but personally never managed to get that working right.
another workaround could be to use lsbox version 2.95 with setting "LsBoxDisableFX" (which regrettably was removed in version 3)
hope this helps