I don't like the grey highlightening on askubuntu, it highlights every two questions, and is just very annoying.
How can I disable it?
since I don't really know why it's being highlighted, makes it also much harder to stop.
One way to do so is to add a tag that you're either interested in, or that gets very little useage (like vpcy which has only one question attached to it on the main site). This would be a stop gap until the StackExchange team produces configuration options for default highlighting
Override the style sheet (a good browser should let you add site specific user style sheets):
.tagged-interesting {
background-color: #f7f7f7 !important;
}