Shortcuts Excel 2007
 

After upgrading to Excel 2007 we've found that some shortcuts doesn't work
and some works sometimes for a while and then we have to close and open Excel
again then they work for a while again.
We use a danish version. Maybe it's language related as I can see others are
having problems with shortcuts in other languages than english.
One example: Ctrl and + (plus sign) doesn't work with the + on the numeric
part of the keyboard.
Ctrl + P only sometimes opens Print.

Is there a reason for this behaviour, anything to be done to correct it?
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LTJ