What ever happened with this situation... I am curious to know

I can understand the frustration, but most of us have never seen this problem. Ever! Not occasionally. Not when working with complicated setups. Never.

I think the source can be isolated pretty easily, you just have to remove the things you have that are different then what the rest of us have. But if you don't have another notebook or desktop you can test with... then it becomes a lot more difficult to do so.

I had this problem today. I got the DLTR-2 version.

Did anyone ever get to the bottom of this?

I was having this problem, as well as intermittent com port errors, until I replaced the USB to Serial cable.

I'm using a MacPro running 10.5.6
Parallels 4.0 with a virtual of Windows XP SP3
MX-850 Editor version 1.12.288
IO Gear's USB to 2-port Serial RS-232 Converter, Model # GUC2322
Gender changer
Serial cable that came with the MX-850

I previously used (without success), a Prolific HL-340, and a Belkin USB to Serial. The prolific kept getting the:
"Error detected while communicating with your Remote Control.
Error code: 100-37UU-0000
Either the com port setting is incorrect (Communications Menu) or the cable is defective."
Well, I had two cables of the same model, and both got this error. Time to replace the cable, so I bought the Belkin F5U409.

The Belkin got rid of the 'com port or cable' error, but then I got this error:
"Invalid Answer - LimitedProgramLoadToPC [DLTR-2]"

So, I bought the IO Gear GUC2322, and all is well. I have read, programmed and re-programmed my MX-850 over 50 times since I replaced the USB to Serial cable, and connections under Parallels and VMWare Fusion is working flawlessly.

add one microsoft active syng in desktop

OK I am getting the same error during 'upload' mx-850 to computer. Downloading seems to be ok as I have done it serveral times and worked out fine. Oh yeah, errror is, Invalid Answer - LimitedProgramLoadToPC [DLTR-2] and also Timed Out - LimitedProgramLoadToPC [DLTR-2] or something like that, but I get a couple different variations of the LimitedProgramLoadToPC [DLTR-2] strain of error messages....these have to be URC codes and not microsoft...so what the heck is going on.

My system just so we dont have to go thru that iteration.
Vista ultimate 64 bit.
gigabyte mobo with the serial adapter on board but I had to add the actual plug part to the back slot. LPT and COM on one slot adapter. This is not a USB to serial it's just that gigabyte is no longer puting the serial and lpt on the rear output plate but still have the prongs on the mobo for the adapters to be added. sort of crazy saving a few bucks when the mobo is an x48 and cost several hubdered $$.
Ram and all the other stuff is completely macked out, my system is less than one year old.
quad processor though q6700
only other thing would be the software version mx editor verssion 1.12.288 I have one version that is not updatable and another that is but it updates to version 1.12.230??? not sure about that but either way both version have same dilema.

OK more info, I can upload and download just fine on an xp machine. so not sure if it's vista.

Well I've had my MX-850 for several years now and have modified it with no problem up until today. Now out of the blue I'm getting this error. What makes it far worse is that no matter what I do I can't even get it back to a usable state!! Any advice for at least getting it to work again would be appreciated - I spent too much time effort and money on this thing to have it brick now...

I'm assuming that URC never even got to the bottom of this issue, did they????

Apparently the program code (and/or registry entries for it) can become corrupt as well. I had remembered that I had some disk errors and ran CHKDSK. After that I had the problem with the error message. The solution (at least for me) was to re-install and use a brand new copy of the editor software. Hope this helps someone else with the same problem...