Ok...
So you were trying to event, and wanted someones ID, so you:
1. Scrolled up to where you wrote it before?
Or
2. Pressed F2 to get his ID?
Or
3. Already had the Player List up and moved the 'Event Window' down to see it?
Then the Send and Cancel buttons failed? Did they do that thing to look like you pushed it inwards? Did you try pressing 'Esc'? Does this repeat, or is this just the 'One Off'?
If you had 2, then did you close the Player List first?