I just installed icq2003b after reading your post, and i do not have any problems minimizing the program. are you clicking on the upper right hand corner button that looks like an underscore _ ?
If your not able to see the buttons, maybe you should change the skin back to "classic", this will make those buttons alot bigger, and easier to see.
Which build of 2003b are you running? I am running build #3916, not sure if there are any previous 2003b builds, but if there are, maybe that was a glitch, check your build version, if it is not the newest - #3916, then you might want to consider updating again.