Waiting for temp... waiting... still waiting...

JV3-250SP being run by Onyx 7.3, on Windows 7 64-bit, through Firewire.

Had a second overnight print do absolutely nothing yesterday, due to a weird temperature issue. Every now and then, when I have multiple things in the queue, it'll run through the first item no problem, and then it'll do its typical wait for the nominal temperature. At this point though, the heat will just shut right off, and the printer will wait all night, showing the target temp on screen, but registering only 25C both pre and post.

If I manually force the printing, the temp will start to rise again, until it reaches its target, and continue on like nothing had ever happened. I really don't think anything's wrong with the elements, as they maintain heat just fine during print time. Anyone ever run into this? Thoughts on progressing?