Windows maps the wrong keystrokes

[hallo]

I am new to virtualbox so please bear with me. I installed VirtualBox 4.3.6 and I'm running Windows 7 on my Mac OSX 10.7.4 machine (the host).
The problem is that when i type letters in the start menu textbox I get the wrong letters. Numbers seem OK, and the the letter mapping is OK everywhere else (browser, search textbox in other windows, etc).
What should I do?

Help is much appreciated. Thanks