ICQ Support: now, to clear things up about the Opera browser:
You must have IE 5.5 or higher installed in order for ICQ to work properly.
it does not have to be your default browser at all, you can use whatever browser that you want.
Udo: This includes ICQ’s website.
Now only missing is a 100% solution for my beloved Opera browser. Because right now, it only works if I set the identity of Opera to Mozilla.
More about the compatibility issues with other browsers regarding the ICQ homepage and client can be found here.
Poor poor non MSIE 5 or up users :'(