Can't Add books, export, switch or create new library

Running 2.7 on Win 10. Long time user with >10K books. Been working fine until a couple of weeks ago (last successful add books was 10/16). Library is on One Drive, suspected that might be problem but I can't switch to a copy on a different drive. Just hangs when I do any of the above. Otherwise looks/works fine. I tried a reinstall but it just kept the old library connection. I have copied the library and tried both 32 and 64 bit versions as well as a step back to 2,69

Debug doesn't seem to indicate a problem since it stops recording when problem occurs. Failing a solution how would I reinstall with no library defined

Thanks
Bill