[Outbackmark]

Those files are something to do with it, as TheRage says, check the write permissions in your directory and change your root password asap, also for any FTP accounts you may have set up.
There have been additions made to FORUMHOME forumdisplay and threaddisplay templates. This code

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has been addred to those templates, the will probably be an xml file of some sort in one of your directories, thats installing this code in a similar way that addons/hacks add code to templates in VB/PHP.
You need to run VB Diagnostics/Suspect File Versions and check all non VB files, most addon/hack files will have recognizable names and alien files can be spotted fairly easily in the report.
I would also suggest you get your host to run a scan in your partition and make sure it's clean.