Strange Bug when running Dungeons

Hell-o there and thank you in advance for your help.

Thanks to the great community and their posts i have managed to set a 5 man boxing to my needs(much work needed to perfect though).
I am using Hotkeynet with FTL and mouseover heals.My strange problem is that when i run dungeons(lvl 20 team =.= ikr....) usually around 1st boss 2-3 of my DPS suddenly stop hitting. The only commands they get from me is follow assist and even loot.
this might have happened once to my healer too? cant recall. Even when i turn off hotkeys and swap to a given DPS windows i still cant fire skills manually.
The only "Fix" i have found is teleport out of dungeon and go back in.But since this aint value for money time spend :P i need to find whats causing this.

Sorry for my bad English and i hope someone has countered and fixed that ^.^