I'm trying to develop some design software based on the A8 engine that works both on a desktop and a Windows tablet. I've confirmed that it definitely runs on the tablet, except for one issue.
Every time you start the program, you get the irritating error "Error E155: Can't open mouse device". Is there any way to circumvent this message? It won't be hard to use Windows API calls to get proper touch screen behavior (and modify my UI system to support it), but I'd like to remove the nag. Any ideas?

Does the touchscreen itself work in your program/game?

A few ideas:
- update mouse / touchpad / touchscreen driver
- update direct x
- set warn_level to a lower number

I have personally have a laptop with touchscreen and get not such an error. Perhaps you can install such a laptop touchpad driver for your tablet? (just a wild idea, I have no idea if it will work)

If you cant find a way but you know there is a working one just hook MessageBoxExA/E and supress the warning.

The tablet shipped brand new with Windows 8.1, so I would assume the drivers and DirectX are up to date. Setting warn_level had no effect.

Interestingly enough, plugging in the keyboard unit (which essentially converts it into a small laptop) not only removes the error but fixes the non-working mouse click events as well.

Unfortunately, we want it to work as a standalone tablet, so this isn't really a proper fix in the long run.

@Ch40zzC0d3r: Interesting thought. How would I accomplish this?

Take a look at Microsoft Detours.
But you should read up a bit on it first, if you fail your game will eventually crash or be detected as virus.