I personally work for an US based company, which uses QTP environment for its automated regression tests runs and IBM DB2 as main database server. And to access this database mainframe, it's required to have an IBM client software (which is the standard method to access databases of any kind).
Today, me and my coworker realized that after some QTP 10/11 installs and uninstalls (can't tell the exactly moment), QTP intentionally changed some DB2 software initialization parameters. Can you believe that? That change made most of the DB2 software not to work, as described in the following IBM article.
No further comments.