http://bugs.winehq.org/show_bug.cgi?id=23438
--- Comment #10 from Andrew Nguyen arethusa26@gmail.com 2010-06-30 13:09:23 --- (In reply to comment #9)
winetricks flash downloaded install_flash_player_ax.exe, but then said: "sha1sum mismatch! Rename /home/mark/.winetrickscache/./install_flash_player_ax.exe and try again." Renaming and retrying gave the same result.
You need to use a more up-to-date winetricks (http://winezeug.googlecode.com/svn/trunk/winetricks).