If you ask in the DOSBox forum you may get a faster response.

have you tried loadfix?

[Moved to DOSBox Games/Apps. Section]

Where's that

However, the computer uses some memory-definitions in its config sys

you were talking about? Your config.sys looks quite standard.

To collector: I think the moderator el_PuSHer belov did that for me. Thank you for the advice!
To roberto: I tried loadfix without success.
To el_PuSHer: Thank you for helping me! I will study the posting guidelines.
To wd: I printed the config.sys from my old Windows 98 computer, where CTREE runs fine (without DOSBox), because you asked me to do that (under the heading Lotus 1-2-3, 2010-5-21, 01:25pm), because that might explain why it did not run on my new Windows 7 computer, which is my problem. There is apparently no config.sys file under Windows 7.

You said that on the PC where that app worked you had some memory-definitions
in your config.sys which i don't see. Which is why i asked for the contents of that file.

To wd: Do you want to see the content of the config.sys again? You said above, that it looked quite standard. What I referred to as memory-definitions were just the lines
device=c:\windows\himem.sys
device=c:\windows\emm386.exe x=C000-CFFF
I did not know if they were standard or not. Sorry!
What would you suggest that I shall do so CTREE can also run under DOSBox on my Windows 7 computer?

FWIW, CTREE 3.2 works without complaint in DOSBox 0.74 using default settings.

CFT Pro 4.1e also works. Both are shareware versions.

Perhaps the memory error occurs because of the size of the database you have built. Have you tried running the program with only its sample data?

Following your first advice I actually found a bug (in relation to DOSBox, anyway) in the program's configuration file ctree.cfg, where "c:\\" should be changed to "c:\". But now the program halts with a new error-message box saying: "CLARION Version 2.0 Batch 2000; C:\CTREE.CFG; ERROR CODE:8 INSUFFICIENT MEMORY; DOS ERROR : 0". Can I make some change in DOSBox' configuration file dosbox-0.74.conf, which solves the problem ?

I think I've figured out what has gone wrong. You have apparently mounted the C drive directly to the folder where CTREE is located, and the app has a problem when it is located in the root of a drive. It puts its path in CTREE.CFG as "C:\\" as you noted above. However, you apparently edited the config file with notepad or so, and I guess you have corrupted its format because it is a binary file, not a text file, thus causing the memory error.

Based on what has happened, you probably did this in DOSBox:

1mount c c:\ctree
2c:
3ctree

You should have something like a DOS folder with a CTREE folder underneath it, then in DOSBox:

1mount c c:\dos
2c:
3cd ctree
4ctree

When the folder is correctly mounted in DOSBox, the path stored in the config file is C:\CTREE\, not C:\\

Unfortunately, when the CTREE.CFG file becomes messed up, the app can't repair it, even if you delete it, so you'll need to restore a good copy of it.

Thank you very much!! This was the solution! Now everything is running! This gave me a lot of trouble, and I am very grateful, that you helped me. This is really a great program, and a wonderful forum.

Have fun!