Noah:
I'm not sure which NI-VISA version you're using, but you might want to consider updating to 3.0. We fixed a slew of bugs related to Serial. To be honest, I don't recall any reboot problems, existing or fixed.
Here's a known issue from the current readme: On Solaris 8, on a Sun-Blade-100, for a Serial INSTR resource, setting the attribute VI_ATTR_ASRL_BREAK_STATE would cause the running process to hang.
I think in a previous version there was some issue where viOpen or viClose tried to always clear the break state, but I can't say for sure. That obviously would have caused a hang in the Blade case above.
Dan Mondrik
National Instruments