Do you know if it's machine related, keyclone related or wow-related?
It's some combination of machine and Keyclone.

We never made any progress on it at all.

I was using the old "mutlibox" software before I migrated entirely to Keyclone, and that didn't exhibit the same problem at all (it had *other* problems, but not that one!) so I imagine it's something to do with the way Keyclone injects keyup/down events, but I can't imagine why that would differ between machines.

At the time, I was following the "one machine, one WoW" paradigm, and my setup was 1xVista32 (main), 1xVista32 (drone1), 3xXP32 machines (drone2 .. drone4, all separate machines).

No matter what I did, drone2 - an XP machine - would NEVER consistently receive extended keys (those with ctrl/alt/shift). The results were exactly as you describe.

I tried changing from a Vista main to an XP main. I bought a 16 port hub so I no longer had any machines using wireless. I made sure they all had exactly the same OS revisions (patches, etc) installed. I uninstalled Multiplicity as a test to see if that made any difference.

And in the end I gave up

Even if I fire up Notepad and literally just lean on the "!" key, I get a seemingly random stream of "111111!!!!1!!111111111!11" (etc) on that machine, whilst all the others receive whatever I typed, so it wasn't specific to WoW.

That's still the case today. If I try to type a smiley on all of my characters at the same time, 90% of the time any drones running on that machine will end up saying "; - 0" or ": - 0" or "; - )".

It's always been a curiosity to me that only Keyclone is affected by this, but so long as the key bindings work it's not an issue for me. I'd sure miss the slash key though - /use hearthstone, /logout, /dance, /ignore, /rude... yeah, I can see how that would be painful!