strange delay by typing some keys on my keyboard

I just installed the plugin "XPrealWX" and the client FSrealWX, using X-Plane 10.31 on Windows 8. The weather-dwonloading works very well. But I'm having the following (strange) problem:

When the plugin "XPrealWX" is in the plugin folder and active, the keys "B" and "L" of my keyboard arent working well within X-Plane. For example when entering a text in the text-box of the VATSIM-xsquawkbox. I have to press these keys for about 1 second to make appear the characters. It's like if there would have a delay of reaction by pressing some keys. That disappeared if i switch to another programm like Firefox, where all keys are working again as they should.

Thats a problem for breaking the plane as well (key "B"), so the brakes aren't working well.

Do you have an idea how i could solve this?

Thanks a lot and cheers
Franz

Thank you, i will try that.