to wipe dalvik cache and cache, you need to be in recovery. what recovery do you have? to get to recovery:
1.power off
2.press and hold power+vol down to get to hboot(bootloader)
3.select recovery
4.depending on what recovery you have will depend on where to find dalvik cache and cache
a. in clockwork mod select "wipe cache partition" then select "advanced" then select "wipe dalvik cache"
b. in amon ra select "wipe" then select "cache" then dalvik cache"
5.reboot
i do these steps anytime i encounter any bugs or glitches. depending on what is going on, most of the time that seems to fix the problem.
hopefully, that will fix your current problem. not sure it will though. out of curiosity what rom are you on?