Microsoft recently released a security update for the Skype for Business client, which seems to be causing issues for people.
The one I noticed first, was the lack of missed call emails being delivered to users.
This script will remove the 32-bit version of the update:
@ECHO OFF
taskkill /IM lync.exe /F
msiexec /package {90150000-0011-0000-0000-0000000FF1CE} /uninstall {6A0E6442-2FD5-499F-9E97-51E3375FF53C} /quiet /qb /norestart
msiexec /package {90150000-002A-0000-1000-0000000FF1CE} /uninstall {6A0E6442-2FD5-499F-9E97-51E3375FF53C} /quiet /qb /norestart
msiexec /package {90150000-012B-0414-0000-0000000FF1CE} /uninstall {6A0E6442-2FD5-499F-9E97-51E3375FF53C} /quiet /qb /norestart
EXIT /B 0
UPDATE: This issue was resolved in KB3114732 that released in February.