Since about patch 5.4.2, I've been getting disconnected from the game. It usually happens during group activity (scenario, dungeon, lfr). It usually happens during fights.
Video driver? My first inclination was the issue was related to my video drivers. So I went to the NVidia site and downloaded the latest and greatest, stable drivers for my GTS 250 video card. No help.
Hardware scan... In the BIOS, my HP desktop has a 'system scan' option. This runs an integrity check on the system vitals, memory, drives, etc. Nothing. I even peeked into the Windows Event log to see if I am regularly getting any failures. Nope.
Network traffic? The disconnect "looks" like I basically hit ESC on the keyboard, backing myself all the way out to the logon prompt.. I've ran a NetMon trace a few times to capture the disconnect, but nothing really stands out. Unfortunately the drop is random, so the log files do get rather substantial by the time it happens.
Other users? Other apps? Thought this issue could be related to background tasks or other user's open applications. I share the PC with the rest of the family. Windows 8 does a great job of flattening other users when they walk away, but ??. Who knows? Maybe IE or my son's Angry Birds is doing it. So I log them all out, shut down unnecessary background tasks (like Steam client and cloud backup of PC) and close all web browser sessions. No help.
Add-ons? I went through and removed or replaced all add-ons in my game that I don't use, or are more than a few game releases old. "Last Update 5.2", gone. I am down to DBM, Bartender4, Vuhdo and a few other miscellaneous addons (postal, bagsaver, tBag). I am running the "Curse" desktop client, so it tends to keep my addons fresh and up-to-date. I don't get any LUA errors, so this could be the issue, but I am not sure I can faithfully group, without Bartender at least. No healing without Vuhdo. So far, no help.
Reaching.. Last week while doing a Windows Update, I noticed that my sound card driver was out-dated. It's the integrated card on the motherboard, but hey it's got a driver. Updated it. Still no help.
Reaching Further... Friday while running LFR, I decided to reset my "Interface" (i.e. video/sound) settings to as basic as possible. I went from High to Good video quality and detail to Basic and Low. Darn if it isn't difficult to raid now as what...I am taking damage?? Oh crap, I must be standing in fire as my character is red, not blue! Move! Good news, I dropped only 3 times while healing during the Shaman fight, not 4.
At this point, I think I am basically to, 1) reinstall game 2) run barebones no add-ons or 3) only run non-grouped content. I am not even sure any of these would fix it. Maybe it's my ISP throttling my connection to Blizzard? Maybe it's the color orange?