Why d I get undefined variable warnings when I launch simulink?

Often, when I try to launch simulink, I get the following response:

>> simulink Warning: simulink.mdl, line 18885: Undefined variable "Simulink" or class "Simulink.SimulationData.BlockPath.manglePath". > In load_system at 21 In libbrowse2 at 19 Warning: simulink.mdl, line 18917: Undefined variable "Simulink" or class "Simulink.SimulationData.BlockPath.manglePath". > In load_system at 21 In libbrowse2 at 19

Subsequently, models fail to load properly and will not operate.

[Kaustubha Govind]

Does it help if you try running "rehash toolboxcache" before starting Simulink?