Please be serious, Yukata. I believe I have described my problem very very clearly, so, please read my posts again.

Before you say "I still coulnd't reproduce your issue", I'd like to ask, have you used two computers running EmEditor v8 and EmEditor v9 side by side, both try ACTION 1(described in my post at 1/5/2010 8:39 am) and observe the difference between the two EmEditor versions? If you did, I believe you can see the difference.

At office, I use Windows XP SP2; at home, I use Windows 7 professional, both present the same problem.

To ToadLoadin: Yes, ACTION 2 works great on EmEditor v8 & v9. I admit from the very beginning of this disccusion thread. The problem resides in ACTION 1.

Yes, I did side by side (one is on Virtual PC), but there was no difference. I am sorry, but I think there is another factor that causes the difference. May I suggest you to uninstall EmEditor and clear all settings, and then try installing again? You can export your settings before you uninstall EmEditor.

----------------
Yutaka Emura
Developer of EmEditor
http://www.emeditor.com/

Well Yukata, now I got your very clear reply. Then I go further try the following:

1. In the afternoon, install EmEditor v9 on a new Win7 and a WinXP machine(VMware virtual machine). As you said, I suprisingly find that they show the correct behavior.
2. In the evening, go back to my home, power on my Win 7 machine, open my documents, like the picture below.

And I again suprisingly find that the Ctrl+Tab behavior still works correctly.
3. Continue my work with EmEditor and other software. About 1 or 2 hours later, I suddenly find that Ctrl+Tab(ACTION 1) works abnormally as described in my previous posts!!!!! Thanks God. I finally catch it!
4. I choose File -> Exit All for EmEditor, then restart it, the bug still exhibits.
5. I log off Win7 then log on, open EmEditor, all tabs restored automatically(an EmEditor v9 feature), now Ctrl+Tab(ACTION 1) returns to its normal(correct) behavior.

BTW: Most of the time, I power off my Win7 and WinXP machine with "hibernate"(only a reboot every 2 to 3 weeks), so that I can return back to my desktop at next computer power on, all opened programs still there. Therefore, I seldom do a Windows log off; I think this makes me more easily bump into this EmEditor v9 bug(probably) than other users.

Yes, I happend to "shut down" my home Win7 computer instead of "hibernate" it yesterday night, so as to realized the fact this night, -- quite fortunate, right?

Please try to simulate my work process to make it appear on your on machine. Of course, I will continue observing how it happend and feed back on this thread.

Thanks for your report. Did you check "Auto Arrange" (right-click on the Tab Bar, select "Arrange Tabs by", and then you will see "Auto Arrange" menu.)?
If so, which of the following was checked, Name, Type, Modified, Active, Ascending Order, Descending Order?

----------------
Yutaka Emura
Developer of EmEditor
http://www.emeditor.com/

Well, I have never realized that "Arrange Tabs by" menu so far. I checked it some moment ago, "Auto Arrange" is not checked.

I tried to check(tick) it, but the symptom does not go away. So I think "Auto Arrange" has nothing to do with my problem.

Now, I'm back to my office starting a new day, still trying figure out the real reason of this problem. Luckily, I get progress!

Now I have confirmed that the symptom is affected by a software called Kingsoft Powerword Dictionary. The current version is called 谷歌金山词霸 2.0 （Google·Kingsoft Powerword 2.0, gciba 2.0 for short）. Website: http://g.iciba.com . It is the derivation product of the most famous English-Chinese dictionary in China over the past ten years, and now this version is free.

Direct download link(57MB): http://download.iciba.com/pwl/powerwordPE_F.25269.3022.exe

While this gciba 2.0 is running, EmEditor Ctrl+Tab symptom arises(no matter it is v8 or v9). After quitting gciba 2.0, the symptom disappears immediately. This is really hard to imagine.

I have further tested this scenario in a clean WinXP virtual machine, the same result.

I'm sorry to admit that I upgrade my EmEditor from v8 to v9 roughly the same time I upgrade gciba from 1.0 to 2.0, so I had almost concluded that was an EmEditor issue.

So, Yukata, if you have time, could you install gciba 2.0(all use default) and debug your code to see why this happens?

A new messege for you, Yukata.

I found tonight that when gciba 2.0 is running(on Win7), Visual Studio 2005 SP1 IDE(run as Admin) becomes completely irresponsive for Ctrl+Tab. Normally VS2005 will respond to Ctrl+Tab and cycle through the list of opened source files.

But in my office Windows XP SP2, gciba 2.0 does not affected VS2005 SP1 IDE's Ctrl+Tab behavior.

So, it is still weird.