You could try copying the DX8 dxinput.dll into the dosbox directory and see if that works.

Hmm, that didn't seem to work though I (apparently) finally found the problem (or at least a solution); Windows comes with a program DXDIAG.EXE which will tell you info about your directx installation; it also seemed suspicious of several files and suggested deleting them; after deleting dinput.vxd, dsound.vxd, and one or two others similar all of sudden dosbox seems to work ok (I didn't need to reinstall directx or anything after that, so I'm imagining those files were left over from my previous installation or something?). Anyway, I can't explain it, but I think that did the trick!

Did DXDIAG tell you why it didn't like the files? Those files are still used by DX9 for proper operation. It sounds like when you updated to DX9 that it did not upgrade those files, IIRC Windows 98 doesn't have a WFP function so once you delete those files the only way to get them back is to reinstall DX9.

So I'd recommend reinstalling DX9 because you WILL need those files (well not the old version of those files), the updated versions of those files from DX9 should work fine with DirectX and DosBox.....if not well then I guess you know the "fix" action.

Hmm, interesting; I ran the DirectX 9 installer again, and it recreated all of the files I deleted. I tried DosBox again and it is still working.

DXDIAG's error message was pretty vague and didn't say what the problem was; unfortunately I didn't note the exact message, but it was something along the lines of "there is something wrong with the files '...' and they may need to be deleted". Really I was grasping at straws when I tried this and was surprised it worked; hopefully rerunning the installer put back everything I need.

Cool. Thanks for replying back that reinstalling DX9 replaced the files and DosBox still works. Sweet. Something else to add to the DosBox FAQ.

Could have been a virus or something else that chewed on your DX9 files, or an incomplete/botched upgrade from DX8.