I just checked with Box's and 2d rectangles, circle and then Simple extrude, add and subtract and no problem in b 34.1
Have you checked that there are no .dwl left in the same place you save your file's, it will have the same name as the original file but end with .dwl, like in "example-1.tcw.dwl", if you have delete them before open TC again after a crash.
V18, V19, V20, V21, 2015/ 16/ 17/ 18 Pro. Platinum
Deluxe V20, V21, 2015/ 16/ 17
Windows 10 Home Premium 64 bit, 32 GB
NVIDIA Geforce GTX 780m, 1 GB