hey,dear sir,please try the following way:

1) I think maybe there are some problem about processing on the DRM.Please try again and reset your computer and then try to play your video .if it's still not ok,please try the second way .

2) what is the DRM removal software? maybe you have to try another one . there are many good choice (just don't use crappy ones like wondershare DRM removal software)
hope i could help you