Problem:


Internet explorer won't start.
This may be caused by a faulty plugin or configuration.

Fixes:


Reset Internet explorer settings


1. Click on Start->Control Panel->Internet Options.
2. Go to the Advanced tab
3. Press 'reset settings'
4. tick 'Delete personal settings' and press OK

Reinstall Internet explorer


Go to the microsoft website and download the internet explorer installer.
or
Try Start->Settings->Control Panel->Add/Remove Programs->Internet Explorer->Uninstall -> Select Repair in dialog

Update Internet explorer


Run windows update and look if there is an update for internet explorer.

Run without addons


You may have a problem with an addon or toolbar.
Try Start->All Programs->Accessories->System Tools->Internet Explorer (No Add-Ons)

Change internet explorer settings


Even if IE doesnt start, you may still change some options for it.
Try Click Start->Control Panel.->Network and Internet->Internet Options

Internet explorer affected by malware/virus


If you cant start Internet explorer it might also be a problem that you have malware or a virus/trojan on your PC. To check for malware I have good experience with the (free) program 'Anti-Malware' from Malwarebytes. For virus scans I can recommend the (free) 'avast!' antivirus software.
It is a good idea to scan for malware/viruses every other while, because a functional virus/malware wont let you know it is there. If Internet explorer was broken by a virus, the virus might be incompatible with the IE version so you are lucky in the end :)