That depends. There is/was a bug in Windows (
fixed in Win7 SP1, but remains unfixed in XP) that can do something like that, but only if you're pressing at least 7 or 8 keys in total, and including at least 1 or 2 modifiers (on a 6KRO keyboard). For example, pressing and holding Ctrl Shift A S D F G H in that order, and releasing in reverse order, will leave H stuck. Once the bug is triggered, the only easy way to get normal operation back is to unplug and reconnect the keyboard (or reboot).