sandboxie
don't know much about anything else, but when i try to create icons my usual way, sandboxie crashes every time. i usually do this by selecting Configure / Windows Shell Integration from the sandboxie menus, and clicking the Add Shortcut Icons button. many folders seem to make the resulting browse window feature crash, starting with the Programs item. can't even roll over it without the menu structure locking up until i get the lovely "close the program" window. i can actually select the All Files and Folders item, and even progress successfully to the chrome application folder (Drive C / Program Files (x86) / Google / Chrome / Application), at which point it locks up so i can never select chrome.exe from inside the Application folder. i could live with this, but then there are the browser issues.
firefox
crashes a lot when sandboxed. usually when i try to download something. often firefox will crash immediately when i try to download something. other times it crashes mid-download. but i finally have to kill firefox all together. firefox works fine outside the sandbox. new install, too; no add-ons, no history... totally fresh.
chrome
chrome doesn't exactly crash and burn on me. it seems to have found its own solution. when i try to download something, it opens the browse window since i have it set to ask where. it even works sometimes. but other times, the browse window is there with all items in it paled out, and nothing is selectable, including the save button. often too it'll be set to my desktop, but the files portion just says, "this folder is empty" or something like that, and i can't select or save anything anyway. again, works fine outside the sandbox.
i'm currently totally stumped. this new machine is a toshiba satellite running win8.1. oddly enough, the machine i bought it to replace is a few-years-old toshiba satellite running win8, with all the same versions of everything, and until this new machine, i have never seen any of these issues.
my total thanks to anyone who actually wants to read this and has any idea what you might try next, and i will happily send you a shiny new nickel if you have a solution. hey, a dollar!

thanks again,
gb