On my BV8 (I am not sure what your BeoVision is) the PC port is AV3 ...
I have to:
a) to press [MENU] on my Beo4 (sometimes twice), and under the SETUP menu select CONNECTIONS, and then select AV3
b) under AV3 select SOURCE to be PC
c) select HDMI to YES
d) press (GO) to store these settings
If this does not help, then I think you need to "play" with the settings inside the BluRay player
First B&O (1976) was a Beogram 1500 ... latest (2011) change has been to couple the BL11 with the BL6Ks *sounds superb*