can spam injection be caused by client pc (author role)?

Hey,

I am writing for a blog and yesterday we found some viagra etc. spam injection in the footer. It seems that this spam was injected since I started writing for the blog and the admin immediately suspected that my computer had a virus causing this. However, I only have an “author” role. Is it even possible to inject spam as an author (in 3.0.4)? The spam was superficially removed and we decided that I try and post something to see what happens. The spam came back about half an hour after my post. But nothing seems to happen when others post something which indeed looks like my computer (or my account) somehow injects the spam when I post something. So, I am a bit worried now that my computer has some infection. An AV scan with Comodo did not find any infections though. What else can I do?

I’ll be glad to hear any suggestions. Thanks!

P.S. I know that it is recommended to do a clean install of the most recent WordPress version etc. (I read everything I could find about this). However, I am not the admin and this is not my task. Rather, I am worried that my computer could be infected and I could not find any information whether something like this is possible (most websites only mention that the admin account should be renamed and the password changed of course).