I recently updated to squeezebox-server 7.4.1, since that my daily alarm does not work anymore.
I use my favorite radio station's stream:
http://opml.radiotime.com/Tune.ashx?id=s8235&formats=aac,mp3,wma,wmpro,wmvoice,wmvideo,ogg&partnerId=16

I can reproduce this, when the alarm time is due, the boom turns on, displays "connecting...", then this status info vanishes, and nothing happens anymore.
The alarm icon (the little bell sign) flashes though.

This stream works for normal blayback without problems.

I use the boom for waking me up for more then a half year, and this NEVER happend before.

I tested another stream, and that works without problem for alarm.

I also thought the boom would generate some buzzer sound, if there is any streaming problem... (I thought I read that somewhere...)