Watching Video: Sound OK but Image NOK (WMP OK) (1 Viewer)

[Miranda]

Hello folk,

Hope you can help me, I don't see directly where the problem can be situated.

MP: version 1.1.0_RC-1_rev25080
OS: Windows 7 Pro 64 bits
Video card: ATI Radeon HD 4600
Codec used for AVC: CoreAVC 2.0 (confirmed by GraphEdit)

Playing AVC files
in Windows Media Player is OK (sound and image OK)
in MP, I can hear the sound going on normally but screen is black

for any suggestion, I'm desesperated