Video/Audio Help

[Erithis]

Ok, so I'm having a majorly annoying problem with my videos. The audio gets dragged out and glitchy, like an echo (not sure how to describe it) every so often during the video. While this happens, the video slows down (which isn't all that obvious). For some reason, this doesn't happen with any new videos I download, which might be because its a different type of file. I'm not exactly sure on this, as I can't test every file I have. At first I thought it might be my codecs, but i've updated every codec i can think of, which didn't change anything. This has only happened recently, mind you, and I did no significant changes to my computer since then. It doesn't matter which player I use either, as they are all like that, albeit, some less than others. The problem hardly happens at all with sound files. I've even checked my task manager and my computer isn't lagging at all to cause it to do that. Its very strange to me, as I can't think of anything that would cause it. I hope its not that the files have been damaged in some way, as some of them are very hard to find.

System:
Windows XP Pro
Intel Pentium 4 3.00 GHZ
1024MB RAM
Radeon X1300/X1550 Series
Realtek AC97 Audio

If you have any questions ask.

[Calum]

X1300/X1550 series - this is not a video card.
What happened before this started, and what players have you tried?
What protection do you have?

[Erithis]

Sorry, I meant X1550 Series, I had forgotten exactly what I had so I had to use dxdiag and thats what it said - I just typed it in without thinking.

Well, there wasn't much that happened before it started, not that I know of anyway. I just went to watch one of my videos yesterday and it started doing that. The players I have tried are WMP, Core Media Player, Nero Showtime, and DivX Player. DivX plays them the best by far, but it still happens sometimes.

And by protection I assume you mean firewall and antivirus. My antivirus is CA Anti-virus and my firewall is the Windows firewall. I have restarted my computer, reinstalled codecs, etc,  anything I could think of, but there wasn't much of an effect.

[Calum]

You need some spyware protection.
Have a look here and get Spybot and Adaware.
Install, update and run them, then post back and tell us if it's any better.
Before you post and after you've run them, try playing the files with VLC (also in the link above).
How well does that work?

[Erithis]

Its not any better. Despite the fact that I removed a crapload of AdWare, it remains the same. Also, VLC plays the files the worst, its extremely noticeable.

Edit: Also to note, its getting worse for some reason, even though I haven't done anything different. It can't be my sound card because the video slows down too. And the chances of it being both my video and my sound card is too slim. I am baffled... Another note, the video has become worse than the audio.