Top 3 fixes for: Internet Explorer won't start, IE7, IE8, IE9 opens then closes immediately

I have been having this issue for years and I found the final solution just yesterday! So I thought I would post it here and hopefully help out thousands of other people like me.

Before I explain the solution let me describe the problem in detail. For some unknown reason, I have always had this problem on my main computer with Internet Explorer 9: whenever I want to run it, a blank window appears for 0.1 second then closes instantly, without any error message or anything. The solutions I describe are valid for Internet Explorer 7 (IE7), Internet Explorer 8 (IE8) and Internet Explorer 9 (IE9). I am running Windows 7 but the solutions also work for Windows Vista and Windows XP.

There are three solutions here, among which two are the official solutions proposed by Microsoft. Let me tell you right off - Microsoft's solutions had no effect, so you might want to skip to the last one immediately.

1. Solution 1: deleting all IE settings so as to remove potentially blocking add-ons
2. Solution 2: uninstalling and reinstalling IE completely
3. Solution 3: running a script that cleans your registry and re-registers missing DLLs

Read on for a detailed description of each of these three solutions.

Solution 1 (by Microsoft)

The problem is perfectly described on a support page entitled "Internet Explorer opens, flashes, and then closes immediately when you start it". That's exactly what happens here, except their solutions had no effect for me. Maybe you'll be luckier than I was?

So the first solution is to reset Internet Explorer to its default settings. After all, the problem you are having might be caused by an add-on that causes IE to crash or something. In order to proceed, either click the above link to download a tool that will clean up your IE settinsg, OR run the tool from your machine (yeah, the tool should already be installed on your machine):
1) Open the Internet Options applet from the control panel
2) Go to the Advanced tab
3) Click the "Reset Settings" button
4) Make sure the "Delete personal settings" box is ticked and press OK.
5) Try running IE again and see if that fixed it.

Solution 2 (by Microsoft)

If that didn't help, you can try their second recommendation, which is basically to uninstall and reinstall Internet Explorer. The process is simple and there is actually no installer to run.
Uninstalling:
1) Open the Programs and Features applet from the control panel (Add/Remove programs in XP)
2) Click the "Turn Windows Features on or off" link on the left
3) Untick Internet Explorer in the list of programs that shows up
4) Restart your computer
Reinstalling: do the exact same, except you tick the box.
If you have an older version of Internet Explorer, I recommend downloading Internet Explorer 9 (offline installer, not one of those stupid web installers that always fail).

Solution 3 by Kai Schätzl - the ultimate fix!

If like me none of the above worked, you must try Kai Schätzl's delicious script. You have no idea how thankful I am, Mr. Kai. Basically, all you have to do is download one of the below scripts:
- If you are running Windows 32-bit, download this: Internet Explorer 7/8/9 repair script for Win32
- If you are running Internet Explorer 32-bit version on Windows 64-bit, download this: IE 7/8/9 repair script for IE 32bit on Win64
- If you are running Internet Explorer 64-bit on Windows 64-bit, download this: IE 7/8/9 repair script for IE on Win64

Once you have that downloaded, extract the ZIP archive, you will find a .cmd file (command-line batch file). It contains instructions that will repair your system and allow Internet Explorer to finally work again. DISREGARD the filename: it's called "IE8" but it works with IE7, IE8 and IE9. To run it, right-click the file and click "Run as administrator".

After it finishes running, start Internet Explorer and voila! You can now use the world's worst web browser again. Download Google Chrome now!