A patch for "The Sims 2 Nightlife" has been released to fix a few bugs that developed with the installation of the expansion pack, namely a problem with the karoke machine. "The Sims 2 University" patch was released at the same time. The "The Sims 2 Nightlife" patch includes the "University" fixes too, so owners of both expansions will only have to download the "Nightlife" patch.
Be sure to back up your files before installing patch.