[Discuss-gnuradio] IndexError: gr_firdes check failed: 0 < fa <= sampling_freq / 2

[md123]

Hello everyone! I am getting another weird error here. i received my USB e4k 
tuner and it was working. On OP25 i was using the scopes trying to figure how 
to get the four lines of dots and with RTL_FM i was getting audio, although the 
quality was bad. So i shut it down and i went out try on high ground but the 
signal was still weak. So i shut it down again, put myself within line of sight 
of the tower, and started it up and now OP25 dies like this:

Traceback (most recent call last):
File "/home/matt/gr-baz/gr-baz-master/samples/op25_grc.py", line 595, in 
<module>
tb = op25_grc()
File "/home/matt/gr-baz/gr-baz-master/samples/op25_grc.py", line 339, in 
__init__
self.gr_freq_xlating_fir_filter_xxx_0 = gr.freq_xlating_fir_filter_ccc(decim, 
(firdes.low_pass(1, samp_rate, xlate_bandwidth/2, 1000)), 
xlate_offset+xlate_offset_fine-fine_click_freq-auto_tune_offset_freq, samp_rate)
File 
"/usr/local/lib/python2.7/dist-packages/gnuradio/gr/gnuradio_core_general.py", 
line 6871, in low_pass
return _gnuradio_core_general.firdes_low_pass(*args, **kwargs)
IndexError: gr_firdes check failed: 0 < fa <= sampling_freq / 2

I have no idea how OP25 (same for RTL_FM) goes from working to failing with 
this error. Anyone have any ideas about this error?

Cheers,
Matt