Application doesn't get installed : insufficient storage available I have around 50MB of internal storage left and some 1.7 GB of external storage left in my phone. But when I try to download and install any application from google android store,I get a message insufficient storage and the application though downloaded doesn't get installed. Why is this ? Earlier it worked fine from the same store.

For instance yesterday when I tried to install whats app I got the same message. What can I do about this ?
I have had this in the past and been able to fix it by rebooting the device