It's not the hard drive upgrade,
It's the change made by an unauthorised Toshiba Technician - I used to work for the biggest Toshiba Repair Centre in Australia..so unless it's different in other countries...
Changing the hard drive itself is extremely simple - there should be a small hatch type thing on the bottom of the laptop that has 1 or 2 screws in it.
Depending on the case they use - it could house the hard drive and the memory, or just the hard drive.
There should be a symbol next to the hatch lid...should be 3 discs ontop of each other. Take a look if you can.
If you can't find it - is it possible for you to take a photo for me and post it here.