Battery charging problem with Dell Venue

Hi,
My Dell Venue android phone has developed a strange problem. It battery gets charged only when the phone is switched off. Neither the USB is detected on laptop nor battery is charged when the phone is switched on. If anyone here knows what could have led to such a situation please help me out as to how to resolve it.
I would have gone to the service center as the phone is still within warranty but i have rooted my phone and run it on CyanogenMod rom hence my warranty is void.
Any help will be appreciated. Thanks in advance.

did you try other usb Cables?
You donot have many options. Restore the firmware on your phone to factory and then take to service.

Thanks for the reply. Reflashing it with MIUI solved the problem. Although still not sure what caused it in the first place.