xul.dll causing CID to freeze and crash

Something really bizarre just started occurring after I updated to newest version - wouldn’t run, got this error message:

This application has failed to start because api-ms-win-crt-runtime-l1-1-0.dll was not found. Re-installing the application may fix this problem.

So I rolled back to my prior version, 48, but now at random times pages won’t load, and when I try to shut down CID and restart it crashes, giving me this error every single time:

[i]Comodo Icedragon

Problem signature:
Problem Event Name: APPCRASH
Application Name: icedragon.exe
Application Version:
Application Timestamp: 57a33929
Fault Module Name: xul.dll
Fault Module Version:
Fault Module Timestamp: 57a34e9f
Exception Code: 80000003
Exception Offset: 008a774e
OS Version: 6.0.6001.
Locale ID: 1033
Additional Information 1: fd00
Additional Information 2: ea6f5fe8924aaa756324d57f87834160
Additional Information 3: fd00
Additional Information 4: ea6f5fe8924aaa756324d57f87834160[/i]

Vista SP1 - love CID, have never had a problem with it before the aborted update happened, but troubleshooting this problem is vexing beyond belief - even odder, when I try to register the .dll, I also get an error message, and it appears nowhere in the registry file. I would hate to have to do a fresh install, I’ve customized the browser to my liking and don’t want to lose the various menus and toolbars, or have to recreate them. I’m thinking possibly of renaming xul.dll to xul.old, trying uninstall, hoping it gives me a repair option, which hopefully will install a new xul.dll - would that work, and has anyone else seen this problem?