letters added at end of commands - corrupt profile?

[elmojo]

Apologies if this is the wrong forum. I tried to pick the right place to ask.
I'm using Civil 3D Land Desktop Companion 2009, on Windows 10 x64, but I think this is a base AutoCAD engine issue.

Recently, when I enter commands, it will often add a letter after I press 'space' to invoke the command. It's typically one of the letters that was in the original command.
This extra letter breaks the command, so that I either have to cancel and try again, or backspace to clear the extra letter before proceeding.

For example, when trying to create a polyline, my command line output might look like this...

Command: PL PLINE
Specify start point: L <- I did not type this 'L'

Interestingly, it never does it if I use the enter key or right mouse click to invoke the command.
My first thought was a bad keyboard, but I've confirmed that it only happens in AutoCAD, so that's ruled out.
I've also checked for Windows, hardware and display driver updates, and rebooted my PC multiple times.

I've basically narrowed it down to a corrupt user profile.
However, reloading the profile (from a backup), performing a repair install on AutoCAD, and following steps found online to clear profile folders/registry entries have not helped.

I'm pretty much stuck. It's driving me batty, and seriously hampering my productivity.
Anyone got any more ideas?

Oh, and "upgrade your ancient AutoCAD" isn't an option.
Long story short, working with certain depts of the US govt has some very odd restrictions on occasion.

[Opie]

Have you slowed your input of the command to see if that may be the issue? I don't remember the version that introduced Autocomplete for commands, which may be causing the issue.

[elmojo]

Have you slowed your input of the command to see if that may be the issue? I don't remember the version that introduced Autocomplete for commands, which may be causing the issue.

I haven't specifically tried doing it slower, but I know that 2009 does not have autocomplete. Thanks for the idea, though!

[cadtag]

way back in the dawn of time. I was doing CAD support for a Ft Lauderdale office.... there was one Compaq 386 DOS machine(which really dates this!!) that would add a string of LISP to the keyboard input at random. We never came up with anything that caused it, and it only happened in Acad.
Eventually the machine was replaced, which solved the problem.

On another note, what US Gov agency is still requiring Acad 2009? I'm working with VA, CoE, and NPS and have not encountered this problem.

[elmojo]

...Eventually the machine was replaced, which solved the problem.

On another note, what US Gov agency is still requiring Acad 2009? I'm working with VA, CoE, and NPS and have not encountered this problem.

So you're saying I need a new PC? I'll tell the wife... lol
I can't say specifically, but it's a branch of the DoD. They are standardized on the r2007 file format, and 2009 is the newest CAD version that natively writes that format. We've tried using a newer release and exporting back to r2007, but they claim they "have issues using the files on their system". Beats me, but I don't question.