I think I have a virus on my ubuntu. How do I get rid of it?

I don't know what makes your system slow, but a virus in ubuntu is really rare stuff. However If you want you can check around on search engines, there are some anti-virus software available (I never used any, don't know which is better!).
Updating your system, if you still don't have the most recent version (gutsy) of Ubuntu, often solves many problems.
About your update problems:
try to type in a console: sudo gedit etc/apt/sources.list and use the find/replace function to replace all the "http" with "ftp" before the repositories sites. It's a very common problem, I had it on three different computers, and this worked with all of them.
Bye.

Yeah, a virus on Ubuntu entitle you to some special prize. I've never heard of anyone getting a virus but I guess it's possible. To run a check install ClamAV. Open add/remove... from the applications menu, change the "show" box to say all available and search for it. Click and install then run.

Thanks for the help guys. The update problems seems solved for now so that worked, thanks. I ran the clamav and it says no virus. But if that's the case then what's causing my system to suddenly mis-behave?

I have ubuntu 7.10(gusty). I've had the firestarter and now clamav. So no virus. As I said before I have just over a gig of memory, only 9% of my hard drive is being used, so I'm now stumped as to why my system is acting up on me. Anything at this point would be helpfull. thanks again.

Open a terminal (apps-accessories) and type

top

See if anything is using a lot of resources. If so, post the info here.

The only thing that's using alot is by the cpu line and it says 98.7%id.
the line reads like this- cpu(s):3.0%us,1.7%sy,0.0%ni,98.7%id,0.0%wa,0.3%hi,0.3%si,0.0%st
tasks 101 total, 1 running, 100 sleeping, 0 stopped, 0 zombie.

I hope this helps you help me. It's what I saw but it's a foreign language to me. I'm sure you understand it though. So again thanks for the help, I know I must be a pain by now.
Thanks.

That's pretty normal. It says about 3% of your CPU is being used (at that point in time) and 98% idle.

Can you give us a bit more info about what is leading you to suspect a problem? What runs slow? When you notice it? Did you make any changes around that time?

Open up system monitor (system - admin) and watch it for a while and see if you notice a lot of traffic or CPU activity - especially during times you feel it's running slow. You can leave "top" running in a terminal too and refer to that from time to time as well.

Also a bit more info about your system would be useful - computer make/model, laptop or desktop, wired/wireless internet, CPU model, new install or running great for a while, etc.

Thanks.

O.k. sorry I took so long but I think I got it. I got fed up so I put my important stuff on a back up drive then started from square one. I reinstalled ubuntu 7.10 along with what ever upgrades I needed and i seem to be o.k. so far. The system seems to be running faster now. It's just my mouse that freezes up but I think I just need a new one. Thanks for all your help.

I ran a scan on my pc with clam and it said i have 7 viruses how do i get rid of them?

@gavoby

Please don't append a new question on a already answered or marked as solved question.
Please make new question from here: https://answers.launchpad.net/ubuntu/+addquestion
you will get better chance to get right answer on a fresh tagged "open" question.
Solved or answered questions are usually not read from answering people.

Thank you