I have windows XP and i had to reinstall it but i

I have windows XP and i had to reinstall it but i cannot reinstall yahoo instant messenger i keep getting the message- Download of File has been cancelled or interrupted.File not completely downloaded. and i dont know why its doing this and when i try to abort it it says Error - the file could not be opened and i cannot remove the old version in the add remove programs bec its not listed there but i can find it in the local hard drives (c:) in the search options so can you help me so i can reinstall yahoo messenger????