It seems that the latest virus definitions from a few companies all have the same false positive in them. This suggests they all share data, either that or one of them has some explaining to do!
We will be contacting the companies & requesting they correct their definitions as a matter of some urgency. Perhaps in the future they will do a better job of checking their definitions....
Testing here seems to suggest it is only triggering on a 20K version of wbload.dll which is included with some of the XP versions of WB. This file dates from 2005 and I suspect its size (it contains almost no code) has resulted in a signature clash where it looks like a different file to the AV apps.
If you are running XP 32 bit it is perfectly safe to allow it to quarantine that file. If the same file gets detected on Vista then the removal of that file will stop WB from functioning correctly, but the Vista file is much larger and AVG seems happy with it.
If anyone has a problem with any other AV packages and wbload.dll please post here so we can contact them and get them to correct their definitions. I suspect Norton AV etc all use their own definitions and so are unlikely to make the same mistake.