Microsoft (Nasdaq: MSFT) is challenging recent FCC findings of problems with devices designed to use vacant TV airwaves—so-called “white space”—for high-speed web access. FCC engineers said earlier this month that tests of the devices from Microsoft and others showed they either failed to avoid interference or failed to detect the broadcast nets. But, according to the Washington Post, Microsoft says another prototype worked during a demo with the FCC, reliably finding the occupied channels and that it sees ways to avoid other kinds of interference; the company plans to file its dispute of the findings with the FCC Monday—rushing to get it filed before the FCC meets Thursday to discuss options for white-space testing.