Like all of you, i experienced this bug. The workaround i have found is to disable the screensaver in the gnome preferences. To balance this, i've told the power manager to switch off the screen around 5min of inactivity.
VLC only have a problem with the screensaver, not with power manager. However, with this setup, you cannot ask gnome to ask you a password when the PC is on again.
EDIT: I have already read what you said about caffeine. As you insist, i'll try it