No it was not heat, was definately something to do with the server - I believe at intervals it checks for registration or something, despite being the full paid up version, and if the reply is late or not received properly, the stream is interrupted. Anyway, I sorted the problem and the stream has run flawlessly for three months - using Icecast2 server without yp, paired with edcast for the encoder. A little more setting up than Broadwave, granted - but free, and with exactly the same capabilities as Broadwave, plus the ability to transmit song titles to players like Winamp and Foobar.
Thanks for the support, Broadwave. Not.