Your know your computer and sometimes you can just feel that something is not quite right. Often it will be nothing to worry about but sometimes subtle changes in the working of your computer can be first signs that something serious is going to happen.

Although the ways in which problems manifest themselves are far too numerous to list here, there are some types of 'bad' behaviour that should not be ignored:

• Blue-screens, crashes, cutting-out, freezes or locks-up - anything that results in the computer shutting down in an uncontrolled way
• If the computer suddenly takes much longer to do things than it used to