It seems to me that there's a lack of communication between your test development group and the other programmers. I agree that overnight tests need to be as robust as possible, but you should not be expected to guess at the new development changes that are happening. Is there some way you can get access to the changes before they are actually released? We work on the automated tests as the changes are being made, or soon after, and we are able to test in a development or test environment before the release to the outside world happens.
This is still not foolproof because someone outside our group can change a program and we might not hear about it, but we find out about it pretty quickly when our test crashes.
And really, a test crashing because the program changed is a good thing, isn't it? I can write you a test that will always pass and you won't ever have trouble with it at night but it will tell you absolutely nothing about the quality of your code.