I upgraded my copy of RStudio this AM to 1,4,1717. Now any attempt to open a help file, whether from the command line or by trying to open the Help window, leads to an immediate crash of the RStudio app. This appears to be specific to RStudio, as the help() command works fine on R on the same system (opens a browser window with the help file).
I am running R 4.1.0 and RStudio 1.4.1717 on a virtual 64 bit Windows 10 (completely updated) desktop.
Update: I just tried this on my home Windows 10 64 bit computer, and the help system works fine. It seems likely to me that there is some sort of permissions issue with the work virtual desktop. I'll ask the sysop to check this out.