in WB configure, basic setting (i think) - there is a box to check to allow WB to use wall supplied...try unchecking it, click apply changes and see if that helps.
does it happen on all skins? or just skins made for WB5? (do older skins cause the same issue?
just in case someone with technical skills drops by, you might open WB configure, click the system info on the left and copy/paste it here