You could try clearing the cache partition as follows (you don't lose any data doing this):
1) Press and hold the Power button and turn the phone off.
2) When the screen turns off, press and hold Volume Down and Volume Up and Power.
3) When the white HBOOT screen appears, use the volume button to move down to “RECOVERY.”
4) Press the Power button to select “RECOVERY.”
5) When the triangle and exclamation appears, hold the Volume Up and Power button at the same time.
6) Using the volume button, scroll down to “Wipe cache partition” and select it.
7) Select “Reboot system now.”