First off:
http://uk.answers.yahoo.com/question/index?qid=20061229091356AA835Hw
Second:
http://forums.logitech.com/t5/Keyboard-Hardware/Can-t-Press-More-Than-TWO-Keys/td-p/143958
Solution would be to maybe:
Chance keys (as some keys are blocking other keys).
Get a different keyboard (good one, gaming for example) and plug it in your laptop.
If the combination is something that goes on you can try this to "figure it out". Don't know how it works but:
ftp://ftp.digitalgenesis.com/pub/keyscan/keyscan09.zip
Probably just press scan and it scans how it works and put you up with specifics
. Really hope it works.... your gonna have to come in-game =[
~Ferret