Keyboard's space bar doesn't work in Minecraft on husband's computer, but it works on my computer

My husband's keyboard's space bar works fine, except in Minecraft. We thought it was his keyboard, so we got another one, however this one has the same problem. So we tried both keyboards on my computer and they work just fine, even in Minecraft. I'm trying to look at the alt-code the keyboard puts out for space, but I can't figure out how to reverse an alt-code. I'm guessing it's some kind of hardware configuration or driver problem or something, but I'm not very knowledgeable in those areas. Does anyone have any suggestions?

Thanks in advance!