Trying to use Arduino as ISP - disconnects from computer when I wire breadboard

So I'm trying to program a proto-board arduino, an ATMEGA328-P chip, through a MEGA2560 R3 board. I've wired it up all correctly but when I add both wires that connect to the positive and negative rails (from 5V and gnd), the sound on my computer which indicates that something has disconnected from the port plays. When I remove either of the wires, the other sounds plays showing that something has been put into the port. I'm not sure if this is part of the problem but I am unable to program anything to the proto-board.

Hence I cannot upload anything even just to the MEGA board when the proto-board is connected, and through some other means I've been able to get errors such as

avrdude: Yikes! Invalid device signature (using the normal ArduinoISP)

avrdude: initialization failed, rc=-1 (when I tried to use a modified version of ArduinoISP as suggested on a forum)

Furthermore, unsure how this happened but the boards.txt file no longer exists on my computer. Is this rectifiable?

Lots to take in there. Thanks for any help provided.

morgsj5: when I add both wires that connect to the positive and negative rails (from 5V and gnd), the sound on my computer which indicates that something has disconnected from the port plays. When I remove either of the wires, the other sounds plays showing that something has been put into the port.

That's a very bad sign. You need to check over all your circuitry very carefully for shorts.

morgsj5: Furthermore, unsure how this happened but the boards.txt file no longer exists on my computer. Is this rectifiable?

Where are you expecting to see that file?