Closing Lid while XP is locked

I have a strange problem and I can't seem to find anything in the archives that is similar. When I close the lid on my I8500 when XP is "locked" (Win+L), the LCD doesn't come back on until I blindly type CTRL-ALT-DEL, my password (which takes XP out of Locked Mode), then Fn-F8 to bring the LCD back on. Fn-F8 does nothing while XP is locked. If I close the lid without locking XP, the LCD comes back on immediately without any keypresses.

What's especially strange is that this behavior stopped for some time but then resumed when I was forced to boot Windows into "Last Known Good Configuration" mode for an unrelated issue. The fact that the problem came back makes me wonder if it's a registry setting?

Anyone with any similar experiences?