Not come across this as I only have a few criteria set in my tags, but it sounds as thought that's hard-coded.
That sounds like an awfully complex tag you are building- can you shorten it at all or post what options you are setting at all?
i know complex. I need more than 25 becuse its all the subnets in one tag. I think its a DB limit because on an other ePO server running 2008 Express there is no limit.