Torrenting causing computer problems?

I recently downloaded uTorrent, and downloaded only one or two items before I noticed my computer slowing down. I have antivirus software, and it didn't report any issues, but my browser in particular was really slow (I use Firefox).

I've deleted uTorrent and all the associated downloads. But when I open Firefox, it often freezes the computer. And I mean actually freezes it — when I Force Quit the browser, I get the rainbow wheel of death and I have to force a shutdown.

But it's not just Firefox. This happens with Safari too. And I've redownloaded Firefox but it doesn't help.

What could be causing this? Maybe it's not a torrent issue at all. But it's strange that it affects all of my browsers.

(Also, I bought a brand new harddrive and 4GB ram recently, so it's not your typical "slow computer" issue.)

 

Good call! There's something called "Firefox Plugin Process (Shockwave Flash)(202)" with a high % CPU. I don't know what it is or how to remove it (aside from temporarily quitting it in Activity Monitor).

Thoughts?

 

Haha, I'll come clean. I didn't download any software, only a few videos (all of which have been deleted.)

Oh, but one thing that's been worrying me is this plugin called Codec-M. I actually downloaded it several months ago, but I learned recently that it's malware (my virus barrier picked it up and supposedly deleted it). Could that be the issue? But I don't know why it wasn't slowing things down before.

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Also, I've got lots of .plist files. Should I delete all of them? I noticed some of them were associated with that Codec-M malware...

 

Apparently .plist files aren't the problem. I deleted all of them and was still able to reproduce the problem.

This is what usually happens:

1. I turn on the computer
2. I open Firefox
3. I search something in the Google sidebar
4. The rainbow wheel of death appears
5. I wait but the rainbow doesn't go away
6. I pull up the Force Quit menu
7. I tell Firefox to Force Quit
8. Nothing happens
9. I have to force a shutdown (by holding the power button for 10 seconds).

I'm realizing that maybe this is a Firefox problem after all… but I've tried redownloading it and that doesn't help.

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I've also reverted to older versions of Firefox (e.g., FF 3.6), but that doesn't fix things either.

 

I've tried deleting my cache, and I've tried reinstalling Firefox itself. Neither make much difference…

I do notice that the problem usually happens when I'm searching on the Google sidebar. I wonder why that would be a problem.

 

I fixed the problem! All I had to do was reset Firefox:

https://support.mozilla.org/en-US/kb/reset-firefox-easily-fix-most-problems

(This was after I downloaded the most recent version, Firefox 13.0, which might also have helped.)