I have previously used the alpha version with no problems. Now I've installed ICQ 3.0(and above) and it quits every time I open some windows.
Please make sure that you're running ICQ 3.0(and above) from its original location.
If you have simply moved the ICQ Application file into the folder of the alpha version, some resources are bound to be missing and ICQ will quit with an error message when it tries to access them.