Thomas,
I had a similar problem recently, a mad workflow was renaming things I didn't want, but didn't show up in my automator's recent items. You should be able to get to it one of two ways.
First, open automator. From the pop up at launch there is a button at the bottom that says
Open an existing workflow.... You should see an Open... window. At the bottom is a drop box that says
All. Select workflows from the box.
Alternitively, go to Users/
your login name/Library/Workflows/Applications/... at this point if it involves Folders it will be in Folder Actions, if it involves documents it should be in the Finder subfolder. I'd just delete it, but I think moving it to somewhere like your documents folder if you want to use it again might work as well. Anyone have an answer? I just deleted mine, no more issues. I'm sure mine was due to shoddy programming in the first place, I blame me.
Hope this helps,
Chris