Without warning or any discernable trigger, one or more modifier keys stick virtually. They're not sticking physically; the keyboard is clean and the keys work fine normally. (And yes, Sticky Keys are disabled.)
Often only restarting Explorer, singing out, or restarting will correct the issue.
(I've also experienced certain keys not working -- usually C, V, and H -- unless Shift is held down. Normally when this occurs, they'll work in some programs (like Notepad) but not in others (Firefox, Chrome, or the Metro Start screen).)
I've tried a variety of suggestions. Nothing's worked, not even a Repair Install for the tyrannical and broken Update 1. And Microsoft's support is worthless. Last night, one tech never appeared before transferring me to someone else. That tech seemed unable or unwilling to address the issue. And when I finally found someone competent, the Send button in the chat window stopped working, so I couldn't communicate with him.
Microsoft are the creators of the Blue Screen of Death, but we ought to be able to expect basic keyboard functionality in their operating systems, shouldn't we?
(Perhaps someone can let Satya Nadella know so that he can put an engineer or two on fixing this. And the fact that Windows Updates sometimes refuse to install if you've modified your Start Menu folders. Yes, the Start Menu that doesn't officially exist in Windows 8.)
Below is a complete listing of every workaround I've attempted (with observations; failures are crossed out) for keys sticking virtually in Windows 8 and 8.1 over the last one and one-half years:
Clean install of Windows 8.1: System ran cleanly for a week. Installed Java (for LibreOffice) and PowerDVD, played some of a movie file, quit, and the Windows key locked (though it wasn't visible on either touch keyboard). Right Windows key?
Coming out of sleep, Windows key was stuck. Opened G700 Logitech Gaming Software to see if key assignments had disappeared again. Started recording a MultiKey Macro and found that the right Windows key was stuck. This keyboard has no right Windows key.
After a few Lock Screens, the right Windows key released.
Then, C, V, and H stopped working in Chrome without the Shift key, and unable to search in Start screen.
Someone suggested that Chrome waiting to install an update was the problem, but this install was up-to-date.
Checked Windows Update; several are waiting to be installed.
(Get keyboard with right Windows key?)
Used KeyTweak to remap RWin to RCtrl. Windows also updated.
So far, so good ....
Uninstalled iTunes, Bonjour, Apple Software ....
Uninstalled Unity Web Player ....
Remove SetPoint, use X-Mouse
Disabled T650's SetPoint Zoom in and out
Press the right Windows key (None on this keyboard, so I can't try it.)
The malfunctions seem to occur often with Windows and Flash updates and/or YouTube videos (whether Firefox or Chrome).
Disable Microsoft Input Configuration Device
Keep keyboard in front of receiver (not blocked by television
Disable "Turn on Toggle Keys" and "Turn on Toggle Keys by holding down the NUM LOCK key for 5 seconds."
Unplug USB mouse (Event Viewer reporting angle errors)
Remove all keyboards from Device Manager, reboot
Pressing Ctrl and +
Press any Function key
Uninstall Logitech drivers and software; use X-Mouse
End jusched.exe in Task Manager
Moved DiNovo Edge USB receiver from USB hub to motherboard USB port
Removed T650 USB receiver
Disabled Touch Keyboard and Handwriting Panel Service
Tapped Shift and Alt
Update of English Input Personalization Dictionary causing sticking?
Don't use Windows Magnifier
Uninstalled Classic Shell, ModernMix, and SkyShellEx.
Okay, so that didn't work. Alarms is gone, and still the keys locked. It was after a long time, and I got a low memory warning. Chrome was running along with iTunes, Origin, and Magnifier.
Pressing keys on physical and virtual keyboards -- and switching virtual keyboards -- seems to have worked ... temporarily.
PowerDVD, USB device, Logitech or Touch processes
Killing BZTRANSMIT64.EXE or BONJOUR released Win key. (Then it reappeared stuck in Touch Keyboard -- but not physically -- until switching to another Touch Keyboard)
Killing Bonjour, some Logitech processes, and turning the keyboard on and off made a difference (this time).
A pointer device did not report a valid unit of angular measurement?
A pointer device has no information about the monitor it is attached to?
A multi-touch device reported inconsistent contact information?
USB issue failing to load drivers?
VLC?Windows Update? Bztransmit64.exe? (overloaded system?)
Disable Intel xHCI mode (?) Enabled USB Legacy Support. Disabling Fast Boot in BIOS not an option with current motherboard; perhaps powering off computer completely (in order to access BIOS; did it clear a conflict Windows 8.1 was saving from restart to restart?) and/or enabling USB Legacy Support might have solved (?) the problem.
Removed unknown from Control Panel\All Control Panel Items\Language\Language options\Input Method
Tap Win (Ctrl, Shift, Alt, hardware and virtual) several times
Detached G700 and T650 TouchPad
Removed Logitech extensions from Firefox, Chrome, and IE. Both browsers have been running for hours. The computer's entered and exited sleep several times.
Uninstalled Zune, iMon
After a Windows Update, no problems for a couple of days. (2/17/13)
Uninstalled and removed all traces of Logitech software (except Harmony); old versions conflicting? IE and Firefox extensions conflicting?
Twice keys stuck when removing DiNovo from base.
Desktop icons starting to stick; using On-screen Keyboard to press NumLock released them. Great!
Signed-in to LastPass?
Press Shift and type with On-Screen keyboard?
NumLock on in Accessibility On-Screen Keyboard?
Update Classic Shell?
Remove extra keyboards from Device Manager?
Device Manager, Human Interface Devices, disable Microsoft Input Configuration Device?
Hold F12 and Numlock (Numlock not present on DiNovo but is enabled on On-screen keyboard)?
Uninstall BetterDesktopTool? Dexpot?
Hold both Ctrl keys for five seconds?
Hold Ctrl + Shift for 15 seconds to release modifier key lock?
Press Fn and Ctrl keys?
Press Ctrl and Alt keys?
Hold both shift keys and F7 together for several seconds?
Control Panel, Language, Advanced Settings, Change Language Bar hot keys, Advanced Key Settings?
Press function key (e.g., F2), then Ctrl?
Shut down, remove AC power, hold power button for 30 seconds?
Remove tweak programs?
Hold both control keys at same time to reset keyboard BIOS?
Stop Human Interface Device Access service (hidserv)?
Enabled Microsoft Keyboard Filter (Services)