I am running MC 9.1.256 on WinXP. If I go to "Web Media", here are some examples of what can happen:
1) Load
"Radiostorm [Alternative] - [Rock] [128k]" into "My Stations". Click it to load the stream. (This is a good example to work with because the "Radiostorm [Alternative] - [Rock] [128k]" is always either very slow, or fails to load altogether, for me.)
2) While the above stream is in "Buffering..." status, try to load the
"BBC News 24 - [News] [33k]" stream which appears under "Featured Stations".
After that, on my system, MC freezes and never comes back, or it simply crashes. The problem will not (always) occur if I wait long enough for the stream from (1) to load or fail to load--I generally have to try clicking a second stream while another is in "Contacting" or "Buffering" status.
This isn't a 100% reproducible problem, in the sense that steps (1) and (2) will
always lead to a crash or freeze, but it's a very persistent problem, in that it happens very often, under the general set of circumstances outlined above.
If (1) and (2) doesn't reproduce the problem for you, try clicking one stream, then another, then another, then another, in quick succession. For me, this makes MC freeze every single time. I know it's easy to say not to be so rough on MC when playing streams, but please understand that this is just a way to get the problem reproduced on your system--for me, I don't have to try that hard to break it (besides, MC shouldn't freeze regardless).