That button is built into the driver, so to stop it you have to modify the registry as I described in the MCE Replacement Driver thread linked in my signature.
If you want greater control over your mce remote try disabling MediaPortals built in support and switching to something like IR Server Suite, HIP or Girder. It's a bit more mucking around but the flexibility is far greater.
But to begin with just try disabling the registry key. If that doesn't work you can recover the registry by re-installing the mce remote driver in device manager.
Best of luck,
Thanks for the quick reply and-81
Cheers