[Avodah] Alleged story about the SM"A

[Noah Witty]

There is "famous" story (I  have heard it so it's "famous" . . . about 
the SM"A who was involved in a din torah, which he lost despite his 
acumen in Choshen Mishpat.  The dayanim explained that they actually 
paskened like the SM"A's own peirush on the matter, while the SM"A had, 
in his own behalf, taken the position of the Sha"Ch, who disagrees with 
the SM"A's peirush. The story is usualy conveyed as a moralality tale 
about the blinding effect of self-interest (negi'os).  (On the topic of 
negi'os in this week's parsha, see Michtav May-Eliyahu, 2:202-203 and 
5:299-300.)

QUERY:  1)    Does anyone have a printed source for this story? If the 
answer is Krohn, pleas identify the book, and possibly a printed source 
earlier than Rav Shwadron zt"l.
                2)   Anyone have any idea what the din torah was about? 
and what halacha was at issue?

Thanks in advance.
Noach Witty