MAMEWorld Forums - EmuChat - MAME input "flickering"

Lately, I have noticed a problem in MAME that is becoming more and more of an issue for me, and I neither know how to best describe it, or where the best place to turn for help would be, but I'm going to try to explain it here with hope for some advice.

For the record, I am talking about SDL MAME which I build in Ubuntu using the latest from the git repository. I also use [A S D] and [Z X C] for buttons 1 through 6.

When I'm playing a game and I press a key on my keyboard, the input is not constant, but has a bit of a flicker to it. I have confirmed this by running any CPS2 fighter and going into service mode and running the input test. Let's say I press and hold A. I see the 1 light up for the light punch button, but it flickers, and I'll see a 0 briefly but frequently light up in that position.

Here's where it gets weird.

Now let's say I hold A down, and press the up arrow for joystick up. Now the light punch button stays constantly lit to 1, and the up direction on the joystick flickers. I can do this again for a third time, say by pressing Z, and now light punch and up will be constant and light kick will flicker instead. If I then release Z, the two remaining inputs will stay constant.

I believe this is only one symptom of a couple of things I am seeing, including negative edge failures (where I release a direction on my keyboard, but it's still registered as being pressed down in MAME until I press it again and release it) and hitches in the emulation where video rendering freezes until some kind of input happens such as scrolling the mouse.

All this being said, I'd be perfectly willing to accept that it may be a function of my own hardware, and may have nothing to do with MAME itself, but I don't see this behavior in any other emulator I use, so something in MAME seems like the culprit. I haven't run this same precise test using a joystick, but I don't believe I've ever experienced the same problems with a joystick, only with the keyboard.

So has ANYONE else encountered this? If I'm only in this, so be it. Just wondering if people might have some idea of what's going on with my setup. Thanks very much in advance for your thoughts.