Yes, you're right. That "evening only" issue has me stumped too. Are there any time based programs running/not running at that time frame? Other than the clock on the wall, what is different about the evening? Nothing comes to mind for an answer.
Could there be some sort of IR/RF interference occurring in the evening that is not on during the day? If you aren't there all day, how do you know the issue isn't also there during the day? Any other IR remotes, controls in the room? A CFB light or some thing? A bad ballast in a fluorescent light, etc.? Don't laugh, I've seen it happen! Is there a WiFi or Bluetooth card active in the PC? Some IR control systems are sensitive to certain ambient lighting systems. I assume that in the evening there would be more artificial lights on? Any CFB or LED or fluorescents?
Hell, I'm throwing spitballs here hoping one will stick. If two IR devices are "sending" at same time in same area (not necessarily line of site - IR does reflect of some surfaces), the signals can interfere. Just a thought. Anyone got better?
Bob, Still Old, Still Grey, And Still A Woolf
No trees were harmed in the sending of this message and a very large number of electrons were asked their permission to be terribly inconvenienced. And a party was thrown for them afterwards for being really cool about it.
Bob's Space - Home Page of the Olde Greywoolf
As I said, PC is custom built, ASUS mobo, seagate HDDs, Nvidia GPU, Intel
Core 2 CPU, 2GB RAM
The keyboard IS called "Remote Keyboard for Windows XP Media Center
Edition". It works over IR, so it is wireless.
If it is the known issue you suggested, still doesnt explain why problem
only occurs in the eveningtime.