Thanks!! And I've just found out that my Gentoo's wine is of 1.2.3, When upgrading to 1.3.37, it fails, too.. After some tests, for each fresh new wine install (i.e. rm -rf ~/.wine) The Following versions didn't work! (Failed to load avisynth.dll) Gentoo Linux amd64 with 32-bit wine-1.3.37 FreeBSD 9.0R amd64 with 32-bit >= wine-1.3.20 The following works! Gentoo Linux amd64 with 32-bit wine-1.2.3 FreeBSD 9.0R amd64 with 32-bit wine-1.3.16, wine-1.3.18 (i have no 1.3.19 package) And if ... (test under FreeBSD) 1. install wine-1.3.16 at first, 2. install avisynth.exe, 3. remove wine-1.3.16 4. do not delete the old ~/.wine 5. install wine-1.3.36 6. wine avs2yuv.exe works!! That is: *. ~/.wine @1.3.16 # works. *. ~/.wine @1.3.36 # didn't work. *. ~/.wine @1.3.16 ? 1.3.36 # works. wine-1.3.20 seems to be the regression point. I've filed a bug report. Thanks everyone.