Wide scale user dissatisfaction.
Supported a rollout of office 2007 with classic menu manager add-in at a Fortune 500 company, the add-in caused extensive problems and performance issues especially with powerpoint and had to be disabled for almost every user in response to issues withoffice applications 'freezing'
Pros: Enabled the vendor to persuade the customer to invest in an unneccessary upgrade to office 2007 $$
Cons: Ensured a very high level of user dissatisfaction which the user's vented on the innocent third party subcontracted to perform the rollout