WINWORD.EXE will not stop running proces

I am using XP pro and office xp pro. i am using word to edit email msgs. winword.exe process will not close after i send the mail so when i compose the next mail it says that winword.exe is being used by another program or can not be found. this is a constant problem of me having to manually end the process for every mail that i send. this just started happening about 2 weeks ago and it’s driving me nuts because i can’t figure it out. Please help.