Hi,
Schematic seems OK for me.
I've use servos on some of my projects with pic and I never had problem even with the same power source.
In one of them I use a 12F675 as a mixer between a RC receiver and the servos, powered by just a 4.8V ni-mh battery.
so...
May be ...
What's your config word (2007h) ?
What are your crystal and capacitors value for the oscillator ?
What are the pulses width you are sending to the servo? They've to be between 1 and 2 us. If not you can bring the servo out of his min/max position, in this case the motor consumption increase a lot ...