Advance Text is a popular Pokemon ROM hacking program. In some cases, after it is downloaded it is unable to open for a particular reason. I'm addressing that reason and how to fix it.
When you try to open the program, you get an error message:
Component 'COMCTL32.OCX' or one of its dependencies not correctly registered: a file is missing or invalid.
There are two other possible components:
COMDLG32.OCX
GRAPH32.OCX
The solution for the GRAPH32.OCX is a bit different, so I won't cover it now.
If you are having any other trouble, this guide will not be able to help you. Sorry.

If the component mentioned in the error is COMCTL32.OCX, go to this site to download the file:
http://www.ascentive.com/support/new/support_dll.phtml?dllname=COMCTL32.OCX

If the component mentioned in the error is COMDLG32.OCX, go to this site to download the file:
http://www.ascentive.com/support/new/support_dll.phtml?dllname=COMDLG32.OCX

You can also search for a different download if you want to. This is not the only source for the file. This is one that was found virus free by my anti-virus scanners. This is the site I used.

When you find the page, right click on the download link and click, "Save Target As." In Google Chrome you have to click, "Save Link As."
When it opens the save menu, go to the Desktop to save it so it's easy to find later. Where it says, "Save as Type" in the save menu, change it from
HTML Document
to
All Files.
Before you save it, clear EVERYTHING in the File Name box. Enter the exact name of the component, including the .OCX part. It will look like this:

File name: COMCTL32.OCX
Save as type: All Files
or this:
File name: COMDLG32.OCX
Save as type: All Files
depending on the component you're saving.

Open this file path for COMCTL32.OCX:
C:WindowsSystem32

Open this file path for COMDLG32.OCX:
C:WindowsSysWOW64

Drag the OCX file that you saved on the desktop into the folder. Now...

If the error message mentioned COMCTL32.OCX, then there will be a file titled COMCTL32.OCX in the C:WindowsSystem32 folder. You just put it there.

If the error message mentioned COMDLG32.OCX, then there will be a file titled COMDLG32.OCX in the C:WindowsSysWOW64 folder. You just put it there.

You're almost done. If you're not the main user on the computer (a.k.a. the administrator), go find the administrator in your home. You will need him/her to allow Administrator access to Command Prompt.
Start Command Prompt.
To do this in Windows Vista, open the Start Menu and type:
cmd
Right-click on the program and click "Run as Administrator"
For any other Operating System, go on Google to find it. Search something like:
Windows XP run command prompt
There should be some sites that explain how to open it.
On my laptop, the Command Prompt screen says stuff about Microsoft Windows Version, some copyright stuff, and a system32 file path. Ignore all of that.

For COMCTL32.OCX, type in the following:
REGSVR32 C:WindowsSystem32COMCTL32.OCX

For COMDLG32.OCX, type in the following:
REGSVR32 C:WindowssysWOW64COMDLG32.OCX

Press the Enter key on your keyboard. If it works, you will get a popup message that says:
DllRegisterServer in
C:WindowsSystem32COMCTL32.OCX succeeded.
This means it worked. The success message for COMDLG32.OCX is very similar, but I can't do it on my computer so I don't know exactly what it says. If it gets rejected, check your typing and try again. You most likely skipped a slash mark or spelled something wrong. Advance Text should now be able to open normally.
Warning : Command Prompt is a powerful program on any computer. Some commands can do serious damage to your computer. A misspell in this command will most likely have no repercussions. However, I will not take any responsibility for anything that happens to your computer as a result of you following these instructions.
This is merely a disclaimer so you can't come after me if you do something to your computer.
Feel free to leave any responses you want, including whether or not it worked for you. If it didn't work, let me know which part you had trouble with and I'll see if I can help.