Wake On Lan Works Intermittently

[tmlp103]

I have 5 PC's configured for wake on lan. If I choose the option to "WAKE ALL" under my selected group there is always one PC that does not wake up. Sometimes it will be PC #2, sometimes it will be PC#4, etc.... Ive also tried waking each PC individually but there still seems to be one PC that wont start. Only thing that fixes it is manually powering on the PC. Then the next try seems to work and the problem is now on another PC.

Any suggestions?

Thanks, Tom