That's a tough one
I have had matrix utils behave in this manner in the past, some of it's dll's would work while others wouldn't that where working previously. Then I started having issues with DBP in general after that, I basically got bored trying to solve it by reading the forums and such, I tried a few vanilla DBP projects that ran fine, then went back to matrix1utils. Normally I would place the msvc dll it needs in with the exe and do nothing else but IanM had stated we could install it in system folders which I then tried. Then all of matrix1utils failed to compile! So I decided I would get on with other DBP stuff only to find I was getting a mix of errors or failed compiles or failed to load dba etc. I hadn't installed anything else, in fact it was fine one night then next morning at some point I noticed. I don't have auto update on ever but had manually updated windows defender that morning before all the apparent discovery and messing around. I got fed up with it quick after that and just reinstalled the OS.
Right now I have matrix1utils installed...once again at some point in the distant past I had done a manual windows defender update - only to find the same thing took place soon after. So rather than trying to install the msvc dll into the system folders like previously, I have left it all as is. I have been using this installation for a long time now and just live with not being able to use some matrix1utils dlls. The ones I need still work and the few other plugins I use aren't affected.
Sorry not of any help. My only real suggested is start with a fresh OS install followed by DBP and STYX - maybe in a virtual machine and see what happens.
Win 7 Pro 64 bit SP1, AMD A4-5300 APU 3.4GHz, 8GB DDR3, NVidia GeForce GTX 750 1GB GDDR5, ASUS A55BM-E