It appears that the current version of d3d9.dll isn't playing nice with USKP 2.0.4, for some users atleast.

With a working load order & enb off, loads fine. (UsePatchSpeedhackWithoutGraphics=true)
Same order, with an ENB (Gameplay Performance ENB) setting that is readily known to work (running under ENBseries v0254) turned on, ctd. (UsePatchSpeedhackWithoutGraphics=false)
Same ENB on & USKP ticked off (turning off USKP also turns off several mods that depend on it as a master), it loads fine.

I didn't test all the way down to just USKP vs ENB.
Dropping in the d3d9.dll from enbseries_skyrim_v0252 resolved the ctd.

Installed USKP and don't have any issue, so i think it's other mods. Scripting in general can't affect ENBoost or ENBSeries, unless it's buggy itself. To work on fix or at least to try out something, you need to localize the reason of the ctd, may be by removing manually mods. And when exactly ctd happen also matters.

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i5-4690k, 16Gb RAM, GTX 1060 6Gb, X-Fi Titanium, Win7 x128
I am INFP, not the brutal, godamnit.

I'm pretty sure all this observation is just a coinscidence. When loadscreen CTD kicks in, attempts to track down it's source just produce all sorts of fake results.
BTW, i use 2.0.4 with ENB 0.254, and my Skyrim works fine.

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i5 2500k@4.0ghz - 24Gb RAM - R9-290 4Gb Tri-X - SSD 240gb Intel 520 - Win7x64

Likewise - no issues here either.

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Intel Core i9-9900K CPU @ 3.6 GHz // GeForce RTX 2080 Ti VRAM 11GB // Win10 64 and 64GB Ram // Monitor 2560x1440@144