mkv file ticked but bs doesn't read it

Hi,
total newbie here.
Problem: i downloaded a movie which is supposed to be an mkv file, but when i start it with bs, i get the "unknown file format" window saying that its a RV40

then error window saying :BSplayer v1.00.810, Unhandled exception at EIP: 00000028
If you click 'Close' application will be terminated.
Please report this info to the author with description what were you doing.
Access violation at address 00000028. Read of address 00000028
EAccessViolation
, 0x0054149F, 0x0054169D, 0x0045554B, 0x0044C896, 0x77D13A50, 0x77D13B1F, 0x77D13D79, 0x77D14374, 0x00542FBD, 0x77E614C7


Question : What the hell do i do ? i mean the mkv box is ticked and Gspot doesn't recognize it either it says it's not an avi file, type unknown.

take care

S.