By Neha Alawadhi (Reuters) - Symantec Corp reported a bigger-than-expected quarterly profit, but the maker of the Norton anti-virus software forecast first-quarter results well below analysts' estimates due to a weak Japanese yen. Symantec shares, which were trading flat after the company reported results, fell 6 percent in extended trading after it gave a weak outlook on a conference call with analysts. "The weak yen is driving a projected foreign currency headwind of $15 million," Chief Financial Officer James Beer said. ...