Windows 8 / IE11 forget proxy settings applied by GPO on reboot

i've run out of ideas here on may causing this. i've toyed policies quite often, never ran problem before.

windows 8 ie11. while there gpo's active on system, settings kept free alter user if need be. use proxy, i'm required provide proxy , exceptions in policy pc's make sure work under normal conditions. added couple of settings in gpp (group policy preferences) correct settings, enabled these settings (green lines) , tested these on test system. work fine, proxy settings pushed through.

then rollout on systems affected (not many, 10 accounts total, in nearby rooms). can run gpupdate /force reload settings, , can confirm proxy settings applied properly. policy seems sound on workplaces needs active on. users still have option change proxy settings on own discretion, that's want happen.

now run problem when part of these pc's rebooted, pc somehow seems decide proxy isn't worth time anymore, , kills settings proxy default. either that, or switches proxy off. running gpupdate /force reapplies policy , starts working again, why windows 8 / ie11 adament forgetting these settings?

the maddening thing on couple of pc's windows 8 , ie11 (and same policies applied) isn't problem , proxy remains filled in, expect gpo's. these include test system, makes me unable replicate problem , test locally.

i've tried enhancing policy using forced wait network become available) aswell forced logonscript run on boot instead standard 'after 5 minutes'. find these under 'computer configuration - policy - administrative templates - system - logon' , 'computer configuration - policy - administrative templates - system - group policy'. neither setting seems work tho. i've tried going computer configuration startup script in request run 'gpupdate' '/force' switches. seems not anything.

in short: know why windows 8 / ie11 falls outside scope of policies, while accepts forced policy update correct settings when 'gpupdate /force' issued manually afterwards? , has idea can make sure policy applied regardless of windows 8 / ie11 thinks should be?

and seems colleague found probable cause after spending 60 mins on this...

tmg client software installed, overrules gpo's push in... removed software affected machines, , check on monday users.

*bangs head on desk, since have stated software not installed anymore*

<sigh>

Windows Server  >  Group Policy