Here are the 5 ways I found in an article on KMWorld dot com (for more detail see the original article.):

1. slow performance : of course no one wants to sit there and wait
2. inconvenience : meaning that what you look for is all the time in different formats like MSWord documents, spreadsheets, presentations, flowcharts for which each time a new software has to be launced. Is to me also a bit like the first point, because that way things become slow.
3. limited functionality : well, it should be able to do what an experienced web2.0 user is used to, and the same for the administrators. I should be sized for you enterprise. Do not use a personal wiki on a stick as an enterprise wiki !
4. no transparency : meaning that the user should not have to know where the info is (on which platform) that he searches. Seams awfully basic, no ?
5. unclear objectives : This puzzles me. Can you exactly know in advance, I quote “what’s really important to users when it comes to finding the information they need to do their jobs”. It’s enterprise 2.0 we are talking. Swarm behaviour. They have to find it and be able to share it. Can’t they decide all along what is important enough to share or to search for ? And I had to smile even more when I saw the next sentence : “Make sure to consider your needs both now and in the future”. That’s nice, someone who needs to know the future requirements of his users. As if knowing the actual requirements is not hard enough already.