I use a Dell Laptop - Inspiron 5100 - Windows XP.
I recently was overwhelmed by many, many viruses on my computer, including adware virtumondo - which invited winfixer and wild tangent. This was all in the past 2 weeks. I have since had someone help me remove the viruses successfully. (But not wild tangent).
However, ever since then, I have had very poor video playback on all my media players, including DIVX, Real player and Windows Media 10.
The video plays (from CD, DVD or computer file) fine for a while. Then it starts to break down, becoming very jumpy/choppy. It mostly affects video, audio seems to be OK. To deal with it, I just press Pause on the player for a while, and then press Play again, and do that over and over. In some cases, I have to restart the machine.
I called the Dell Technical Service line and they had me run a hardware diagnostics and check the DVD player for any damages - the computer passed the test so they think it is a software problem.