I think that Ndless requires an even more old version of the 1.1 OS.

I was just looking around and saw this: http://www.unitedti.org/forum/index.php?showtopic=8191&st=300

ExtendeD says he is using v 1.1.9 back in 2009 so i think it should work.

Edit:

I was just reading through the source files and is had a header for os_cas_1.1.9170 the same version I am using

Edit 2:

I was going through the source files and I can only find it checking if the version is 1.1.9253 which is only available for non cas nspire calculators, did  I just miss the cas calculator part or does ndless only work with non cas nspire calculators

If the problem isn't in the OS, then I don't know really what else could be causing this. I myself own a non-CAS Nspire, on which Ndless worked perfectly, so I don't really have any experience with the CAS version.
I have a friend with the CAS one and Ndless works perfectly on it. I have no idea why it isn't working an your calc.

If you got 1.4, uninstall it completly then install the above. Do not plug your calc until 1.3 is installed completly.

Not necessary. You can install both version on the same computer in two seperate directories, it works perfectly (same for TI Nspire Computer Software 1.7 and 2.0)

Also, if you use Windows 7 you will need to do this to get 1.3 to run on it (1.3 wasn't compatible with Windows 7): http://ourl.ca/4200/77438

1.3 is compatible Windows 7 64 bits. You just have to get the Vista Driver and Install it as administrator.
more details (french) : http://tibank.forumactif.com/problemes-divers-f9/windows-7-64bits-et-nspire-t4830.htm

If this is not the problem you have, then I'm not sure what is it.

Well, I think his probelm was mine when I tried to install Ndless (on Win7).
Ndless need to install OS 1.1 in every case, either the OS 1.1 is installed or not. If you have the *.tnc or *.tno 1.1 OS file, you need to put it in [Ndless_dir]/userfiles directory (create if not any), and rename this file to "tinspire_1.1.tno" (*.tnc also, rename it to *.tno).
Then, Ndless will get this file instead of trying download it from TI-bank. It will install OS 1.1 one more time.

1.3 is not compatible with 7 64 bits. There's that workaround about drivers, but just that shouldn't even be supposed to happen at all if it was really compatible. Not to mention under windows 7, Computer Link Software 1.3 freezes when exiting (have to shut it down using CTRL+ALT+DEL)

Thus, 1.4 is not compatible Win7 also. I have to Ctrl+Alt+Del all the time even if I re-install it with the 1.3 uninstalled...
I can trust that 1.4 is designed for Win7, but not that 1.3 doesn't work better than 1.4 :p
(It depends of a lot a parameters...)

Really? Strange, I never had this happen.

the entire mistery of Windows :p
That why I said that it depend of a lot of parameters...

But what I meant is that 1.4 was designed to be compatible with Win7, while 1.3 wasn't. That's all I'm saying. Don't imply 1.3 was made to be compatible with Windows 7. I don't even know if Windows 7 was even out when 1.3 came out anyway.

Ok, we are on the same way now.
- 1.3 works with Win7 64 bits, and is needed to isntall Ndless v1.0.
- 1.4 is needed to install OS 2.0
- We can install 1.4 in an other directory, both version will works.
- On the other hand, 1.3 is not designed for Win7 whereas 1.4 is.
- For my personal use, I saw that 1.4 is full of bugs with Win7 64 bits (connection lost, freeze...)

Quote

- 1.4 is needed to install OS 2.0

I don't think this is true.  I have 1.3 and I have successfully sent OS 2.0 several times to several different Nspires (all non CAS)

Yeah, I've sent 2.0 with Linking software 1.3 as well