outlook express and office xp

we just loaded office xp onto some of our pc’s and on two machines we are having a problem in outlook express. when we send a message we get a spell check error stating that spell check was halted. what could be causing this. this did not occur with the office 97 pacakge on these machines. we have downloaded and redownloaded internet explorer 6.0 on these machines also and this did not resolve the problem. these machines are running window 98 second edition. any suggestions sure would help. thanks.