Intel(R) processors feature Intel(R) Turbo Boost to be able to increase its stock clock speed (2.4 GHz in your case) in certain moments when there is unused resources from the processor and if the system requires more processing power.
In the other hand, it also features Enhanced Intel® SpeedStep® Technology (EIST) which enables the processor to run at lower frequencies adjusting dynamically according to the processing requirements. (As a side note, Turbo Boost relies on EIST to work). So, seeing the processor running at a lower frequency would be normal depending on system usage.
What you should do in this case, would be to check with your laptop manufacturer directly in order to check the settings of the system according to what they have defined as best for your computer, and make sure that the hardware installed is working as they tested it.