Lost packet messages

[irkuck]

When playing TV (vlc 0.7.0 WinXP)from satellite streamed over LAN, vlc shows all the time this kind of messaages:

Example from HDTV Astra:
mpeg_system warning: packet lost by TS demux for PID 4716: current 5, packet 7

Hot Bird channel:
mpeg_system warning: packet lost by TS demux for PID 260: current 8, packet 10


Those PID's are not video or audio. I can not say if they are PCR or other PID's. Can you explain what might be those PID's and why they are lost