I've been having similar issues as far as Alice locking up. Usually in the middle of something it will freeze. Eventually, five minutes later, I get this message saying that Alice has "Stopped Responding" and do I want to "End Task". It may seem like a big thing, but the problem can be avoided by saving OFTEN, and occasionally closing Alice and then restarting it. I'm pretty sure it has something to do with ALice using too much memory.
How many MB of RAM does your computer have? What's the size of your virtual memory cache? What is your processor's speed?