hello guys, I am facing a problem in matlab i.e I am using ode45 to solve a diff. eqation and whenever i changed the parameters of the system

hello guys, I am facing a problem in matlab i.e I am using ode45 to solve a diff. equations and I run the program with some system parameters like mass stiffness and damping;i can easily execute the code and get the results in no time but whenever i assigned new parameters of the system or i change the system parameters ,it'll take hell lot of time to execute or sometym it keeps running ...can anybody tell how it is and whats the reason for this please do reply !!!!!

[Star Strider]

Please post your code, and the parameter sets you have been using.