Problems with Logitech LX700 Keyboard

[effowe]

I have been using this LX700 for about a year now. I play CS:S frequently so there are times where I have to crouch (CTRL) and jump (Space) at the same time. Lately my keyboard hasn't been picking up this combination of keys. I thought that the batteries might be going dead, so I replaced them, but that didn't help.

Is there anything I can do to remedy this? Any suggestions would be much appreciated.

Thanks