After installing Vensim DSS in a Windows XP bottle with a registration code, the next time it was run Vensim did not recognize that it had been registered. Installing Vensim DSS in a Windows 98 bottle fixed this problem. (I did not try a Windows 2000 bottle.)
This observation was based on the following configuration: Vensim DSS 5.8b, CrossOver 7.1.0, and Mac OS X 10.5 (Leopard)