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Any ideas what would cause keys to be stuck "on"?

3842 Views 6 Replies 4 Participants Last post by  protovision
I built one of the HTPCs in renethx's guide, and it has worked great. About two weeks ago it started acting up. I will be using the keyboard or mouse, and the computer will respond as if I have the alt, ctrl, shift or windows button held down. It appears to be random which combination of those buttons is active, but it's always one or more of those four. I can launch my Kaspersky Virtual Keyboard to see what the computer thinks is being held down. I'm wondering if anyone here has experienced this before, or if this is related to some of the programs I use specifically related to my Home Theater activities.

All the software/hardware I use for this computer:

Windows 7

Windows Media Center

Media Browser


Media Center Master

IR extender from Monoprice

Harmony One remote

Imon software

Microsoft Office

Chrome browser

-It's not the keyboard. I cleaned it, no help. Then I bought a new one, no help. I have tried three different keyboards (1 wired USB, 1 Wireless USB, and one PS2)

-I have tried 2 different mice - 1 Wireless USB, 1 Wired USB (there is no PS2 plug for a mouse)

-I was using windows drivers for the mouse/keyboard. I installed Microsoft drivers for the specific keyboard mouse combo I have. Didn't help.

-It's not the Sticky Key's option on the control panel. I checked that.

-I did several scans with several programs for Malware, Spyware, viruses, etc. It's clean.

I'm hoping this is related to something HTPC specific, because I have been working on this for two weeks now and it's driving me nuts!

Thanks a million for any ideas, help or suggestions you have!
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I had a similar problem with a pc with XP a few years ago, I formattes the hard drive and relpaded Windows and it was fine. Never did find out what caused it, the keyboard was fine.
I too am experiencing this EXACT problem, and have gone through the same trouble shooting things that you listed above. I am running a Thermal Take DH102 case with a Harmony 1100 remote in iMon PAD mode.

To reproduce the problem on my system:

1) Set focus to the desktop by single left clicking the mouse

2) Press the "Ok" button on the Harmony which issues an "Enter" command.

The system behaves as though the Enter key is stuck down. Pressing the Enter key at this point (or any other key) does not stop the runaway Enter keypress event.

Some background information: I am running the Logitech RF extender so there is no chance of IR feedback triggering multiple Enter key presses. I am also running a Logitech wireless Anywhere mouse and K340 keyboard, through their Unifying receiver. When the pc is freaking out as (I believe) iMon is issuing multiple return key events, I can unplug both the IR port and all Logitech equipment. The PC still is in a state of repeated Enter key press events.

I apologize for bumping an old thread, but I have exhausted just about all avenues for help. This was one of the few forum posts that seemed on topic.

Any advice anyone?

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I'm just curious, how do you know for sure it's not IR feedback? That was my problem in the end.

I found that if I unplugged the IR extender while the problem was happening, the problem continued. However, if I booted up the computer without the IR plugged in, the problem never occurred. Maybe try it, just to be 100% sure because it's easy to test.
Thanks for your reply Guaps, I'll try that.

I didn't think it was feedback for 3 reasons.

1 - Not all commands issued to the HTPC through the Harmony were repeated. I obviously haven't tested all the commands, but up, down, task switch, app start etc. work correctly, where as other such as windows key, return repeat wildly.

2 - The harmony remote communicates to the RF extender (not IR extender) through radio frequency. Once the extender registers this signal and converts it to light, there's not closed loop communication through IR or RF to the remote that the command was issued.

3 - Just to be sure, I completely cut off the IR path to the HTPC by unplugging the direct line in and covering the IR sensor. As you stated though, the problem was already occurring at that point.

Again, thanks for your reply!

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So here's what the problem was. When the Harmony remote was programmed, I used the IR command for 'Enter' as mapped to the Ok button directly from the Logitech database. I'll explain how to correct this later.

A brief explanation:

It turns out that a timing issue allowed the Key Down (Enter in this case) event to be registered, but the corresponding Key Up event never went through. The result was that the PC acted exactly as it should, as if I were holding down the Enter button on the remote. Increasing the inter-key delay within the Harmony software didn't correct the issue as Key Down & Key Up are issues in pairs. The inter-key delay is introduced after that sequence completes.

To correct this issue, I removed the stock Logitech supplied 'Enter' IR code that I had been using, and replace it with IR code learned directly from my iMon supplied remote. This has corrected the issue completely, whether I issue the command through IR directly from the Harmony, or through RF to the RF Wireless Extender and then through IR from that device.

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I've run into a similar issue in the past with my wireless keyboard, where a key would keep repeating even when I'm clicking nothing.

In my case, it was a similar cause, for whatever reason, my IR receiver missed the 'key-up' (key released) event, and therefore kept thinking I was holding the button. Typically mashing on the keys and all the modifiers (alt, shift, ctrl) usually fixes it, one of the keys is the 'key-up' event its waiting for. Not a great fix, but it works.
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