Personal privacy is affected by the occurrence of adware and spyware in peertopeer tools. In an experiment, we investigated five file-sharing tools and found that they all contained ad-/spyware programs, and, that these hidden components communicated with several servers on the Internet. Although there was no exchange of files by way of the file-sharing tools, they generated a significant amount of network traffic. Amongst the retrieved ad-/spyware programs that communicated with the Internet, we discovered that privacy-invasive information such as, e.g., user data and Internet browsing history was transmitted. In conclusion, ad-/spyware activity in file-sharing tools creates serious problems not only to user privacy and security, but also to network and system performance. The increasing presence of hidden and bundled ad-/spyware programs in combination with the absence of proper anti-ad/spyware tools are therefore not beneficial for the development of a secure and stable use of the Internet.