Follow this link for more general information (do not fully trust this as your problem may be different) http://www.techhive.com/article/141516/article.html
This is a common issue and anything can be the problem. You are messing with potentially (120 Volts,60Hz) for Canada, slightly higher for Mexico and a lot more if you go outside North, Central or South America. Do not try to fix this yourself or work on theories because without a professional looking at it you might be putting yourself in danger.
However, as an engineer i may be able to help with your curiosity given more information. Such as when this started? Have you charged your laptop outside Canada and Mexico? how long do these shocks last for? Myself and other guys here i'm sure we can help to our best knowledge but without physically testing the system we could all be wrong.
Here is a list of potential issues:
- Battery is faulty as the link suggests
- Motherboard is not grounded properly
- You visited another country whose mains function at different frequency and voltage, you used your charger (which you shouldn't if it is rated by Canadian Standards ) eg Zimbabwe (220Volts, 50Hz). As a result, you blew your motherboard creating a short circuit. Even with a convertor this could go wrong
Now you see the wide range of problems, hence this is important you take it to a professional who can physically test for you.