Whenever I try to load Brutal Doom as of late, I just get the following error as seen in attachment.

I tried following two possible fixes from here:

http://www.moddb.com/forum/thread/brutal-doom-bug-on-gzdoom

which were by shanestrife AlexNitro44 but they did not work. 7zip refused to save my code changes and showed duplicates of certain files in the graphics folder. Deleting the offending duplicates didn't help either and neither did deleting the mod entirely and and unzipping it afresh.

before you had the issue, did you change anything at all?

Not that I can think of no. I hadn't played this in a while and it worked fine last time I'd played It before now. I uninstalled Doom 3 BFG where only one Brutal Doom was, but I put it back because I remembered afterward. It was when I was testing the BFG Brutal Doom that I found out that all of them had this issue. That seems to have done it, but now the DoomMetalVol4.WAD music doesn't work for brutal doom. It does for GZDoom however, but only when dragging the file to the exe.

The error is because the letter l is present in the two numeric values for A_FadeOut in the Blood.txt file inside the Brutal Doom PK3 so it is 0.l instead of 0.1. It has been confirmed by the author that the l should be a number 1 and it will be fixed in the next release, but you can edit it yourself if you wish.

I say it has been confimed as being meant to be 0.1 (rather than 0.01 and 0.03 as in the article you linked to) because the same code is used in the author's Brutal Doom 64 mod, but there he has fixed the issue so that the letter l has been corrected.