Cisco Clean Access has been a big distraction since it was used at my university.
Prolonged bug that has not been fixed (list):
1. Cisco NAC Agent does not recognize new versions of Antivirus or other antivirus products in market. This result in users have to buy antivirus products that are limited by Cisco. That actually restricted the users' choice of antivirus. User should have the freedom to choose their own antivirus, not Cisco. At the time of this writing, Cisco NAC Agent does not recognize Avast Antivirus 6. When I first moved in to the University, Cisco NAC Agent did not recognize Comodo Internet Security (Full Antivirus and firewall included). And that forced me to install AVG on my three computers while I have big homework and exams due.
2. Even if your antivirus is on the Cisco preferred list, you may not be able to update your antivirus signatures/database if you have temporary access at that moment - some antivirus signatures/database update servers are not on Cisco's whitelist. That means you have to install an antivirus product that is on Cisco's white-list and the antivirus update server is also need to be on Cisco's white-list. The only way to find out that you have the antivirus that is Cisco approved is to try it yourself, because the school never disclose the approved list.
3. After a logout of Cisco NAC Agent, you may not get another pop-up prompt window to enter your username/password to login for next 5 to 10 minutes. Say for example, I am using google docs and I wanted to print or save my work, a disconnection of 5 to 10 minutes is a great distraction.