Windows Updates - Conflict with Avast Pro A/V? - Microsoft Community

my windows: windows 7 x64 ultimate

last month (3/2017), ran across appears problem/conlict between avast pro antivirus , windows updates, with:
march, 2017 security monthly quality rollup windows 7 x64-based systems (kb4012215) , update windows 7 x64-based systems (kb2952664)

initially installation of these updates failed.  then, after trying again, install appeared have succeeded windows wouldn't load afterward. @ boot, the login loaded slowly, after logging in, come blank screen mouse pointer (moveable, not frozen).  using system restore brought pc was.  also, boot in using safemode (with networking), , worked fine in safemode.
later tried updates again, , avast pro made me install update. same problem returned.
tried uninstalling avastpro, installing windows updates, and reinstalling avastpro a/v. same problem returned.

basically, have found if both avast pro , above updates installed, windows won't load- normal boot becomes stuck.  have contacted avast on issue, no response yet of post...

so question is: reasons there problem occur?  there modification make in windows fix it?  have used avast while well, approve of it, , keep using it.

i built pc in 2009 (year of win7's debut) , upgrades have included an ssd. still good, fast pc.  job replacing pc hardware, , have put skills maintenance of pc.

update: a solution (4/21)

i looked at services, security settings , local security policies.  avast service logs on local system.  changing avast service logon (in safe mode) to windows user account (an administrator) resolved problem.  don't know created problem... somehow windows security updates changed a setting.... or else don't remember change made security setting in past, , windows updates undid this... seldom mess services , security... 

Windows / Windows 7