I have same problem, only been getting it last few days. Linear static study of which I have literally done thousands of. When I get the message I cancel study and run it again then it seems to get over it and move on. Not a fix though sorry.
Samuel, do you have parts treated as shells or beams in your model? Bolts? The special loads could be the bolt tensions which SW has to treat first before doing the other analysis. One thing I had done differently in my current model was allow SW to treat some thin sheet metal parts as shells. I dont normally allow this as I have had problems with shells in the past, you can use them ok for pressure or bending maybe but you cant apply a load on the edge so it doesnt suit what I am trying to do. It may have a similar bug up its butt with regards to bolt loads. I have changed my parts to solids which then requires mesh control to suit the thickness of the sheet metal part but it seems to be going as per normal now.