When you are shutting down a system properly, the OS has a number of housekeeping things to do, ranging from physically writing dirty disk blocks to safely closing all the open programs from spreadsheet to a database program.

Now, when you force shutdown a PC/Laptop, the power goes off in a few milliseconds time and the OS has no time to finish all these functionality. So, You can categories these errors as two parts,

1. Hard Errors, errors which causes hardware defects : These are mainly caused because of power supplies. There is a definite reason why PC has a SMPS installed. When power goes off immediately, it can cause many defects in motherboard and hard disk. Motherboard errors are rare, but hard disk errors can be expected, if you are a frequent user of "disruptive shutdown"(this is an MS terminology).


2. Soft Errors, errors which causes software malfunction : These are software errors, due to incomplete configuration file or presence of temporary file. These errors are recoverable and non-lethal.