If I were to guess, I would say that it was the FANTOM driver (LEGO/NI's communication driver for NXT communication) went into a "time-out" mode because the BT link got lost to the NXT.
Basically... the NXT dropped the BT somehow, Fantom was in the middle of connecting... then locked up because it couldn't find the NXT anymore... and then ROBOTC "froze"... ROBOTC would have come back alive after about 30 seconds, once Fantom finally timed out fully and returned to ROBOTC that it had.
If it keeps happening, we can investigate it a little more using the message log... but I think may just be the joys of using BT and having it disconnect.
On a side note, I hear Newegg is having a sale on USB extension cables...
ROBOTC Developer - SW Engineertfriez@robotc.net