if its a virii, trojan or any type of malicious file how can it piggyback on a plain old ASCII txt file

in XP it seems to corrupt msgplush.dll (for msn messenger plus! from patchou), i uninstalled that and messenger is OK now- the problem is gone

if this is a virus its a damn good 1 - because it seems to target only me!

ive been round his house sending the files as well and its nothin he is doing, his computer was using windows me as mine was - he wasn't doing it on purpose, and it was any filetype, and it was only me