Caps Lock on Windows 7 Guest doesn't work on first key

[HockeyBum27]

When I turn on Caps Lock in my Win 7 guest, the first alpha pressed after turning it on is not in caps.

My system:
VirtualBox 4.3.14 (Guest Additions same version is installed on guest)
host: Ubuntu 12.04 64-bit on Dell Latitude Core i7 laptop, 8GB ram 256GB SSD
guest: Windows 7 SP1 32-bit, 512MB RAM, 10GB HD

Initially I thought it was a timing issue (e.g, typing too fast, as described in a similar post for Windows 8 ), but through testing I found it was not.
Here is what happens:
When I am typing in the guest in an application (e.g., Notepad, cmd, etc.):
- when I press the CAPS LOCK to turn *ON* caps, the next alpha letter I press (e.g., 'a'), the FIRST letter prints in lowercase. All subsequent alpha letters print in uppercase.
- when I press the CAPS LOCK to turn *OFF* caps, it works fine - that is, the next alpha character I press is lowercase.
- if I just use the SHIFT key (instead of the CAPS LOCK), all works as expected.

It does not matter whether I switch to a non-guest window (e.g, terminal, geany, etc.) and press a key - when I come back to the guest, the first key I press there (if it's an alpha key) is lowercase. Pressing the Host key has no impact as well.

Also - I am using an external keyboard (USB of course) connected to my laptop (for ergonomic reasons). However this happens regardless of whether I use the USB keyboard or the built-in keyboard.

Attached is my log file. Thanks in advance for any help on this!

[HockeyBum27]

UPDATE: after several days of this, I notice this morning that this issue has disappeared. No VBox updates have been performed in the interim; the 'recommended system updates' on my system (Ubuntu 12.04 64-bit) are the only updates that have occurred in this period.

I will post an update if anything changes (or even if not, after several days), but I would still like to know what may have caused this.