Danny,
Frequently, I have the image preview up and then I bring up the IPTC dialog. If I use Alt and the arrow keys to traverse across three or four images, the first character I try to type after that in one of the fields in the IPTC dialog is usually garbage. With the way I have my substitution codes set up right now, I am usually typing a number using the numeric keypad, but I can recreate it with the regular letter keys as well. I think this bug has been around for quite a while, but I've only recently figured out how to recreate it fairly consistently. In case it matters, I'm on 64-bit Vista Ultimate, but this used to happen on my older XP machine too.
I'm able to reproduce the problem but I'm not sure what I can do about it. Let me explain. I added some debugging code to print out what key input was occurring. Here is an excerpt with annotations:
c:0 a:1 s:0 msg:260 wParam:39 (Alt-Right arrow down)
c:0 a:1 s:0 msg:261 wParam:39 (Alt-Right arrow up)
c:0 a:1 s:0 msg:260 wParam:39 (Alt-Right arrow down)
c:0 a:1 s:0 msg:261 wParam:39 (Alt-Right arrow up)
c:0 a:1 s:0 msg:260 wParam:39 (Alt-Right arrow down)
c:0 a:1 s:0 msg:261 wParam:39 (Alt-Right arrow up)
c:0 a:0 s:0 msg:256 wParam:65 ('a' key down [produced a box character])
c:0 a:0 s:0 msg:257 wParam:65 ('a' key up)
c:0 a:0 s:0 msg:256 wParam:65 ('a' key down [produced a letter 'a')
c:0 a:0 s:0 msg:257 wParam:65 ('a' key up)
KEY: c=ctrl key down, a=alt key down, s=shift key down, msg:Windows message code, wParam:key code or ascii value
As you can see from above there is no difference in the event that produced the box character and the event that produced the letter 'a'. The text field (not written by us but by Microsoft) just happens to output an incorrect character when it has had the Alt-Right Arrow key sequence sent to it a few times. Using the other keyboard shortcut (Alt-]) does not cause this problem to happen. Why it happens in the first place, I don't know. Unfortunately I cannot even detect that it is going to happen by checking the key events.
So I'm not sure there is anything I can do to solve this issue. The workaround is to use the Alt-] and Alt-[ key combos instead.
-Kirk