copy-paste outlook 2003 problem

When I copy from a mail into a new mail, it doesn't paste, except when the new mail is already open. I tried the "detect&repair" option, but didn't work out. We are using Exchange 2003 with outlook 2003. Anyone knows a solution??? Maybe a known bug? MsOffice2003 is installed locally on the pc's and laptops. Some of the machine have this problem... not all.