SPR has always run a seperate mIRC instance when generating the list, it does this so the mIRC you're using doesn't feeeze during the operation, and it would. Notice there is listbot.ini in the SPR directory, that is the mIRC configuration file ($mircini) SPR uses for the new mIRC instance. Also, SPR Jukebox is outdated by a few years, last release was 2001 and was not coded for mIRC v6.x (lacks multi-server support among other things), you should try
OmenServe instead.