What is wrong with my internet access and other window systems' speed got slow?

around these days,my pc internet access speed become very..very........... slow, and sometimes couldnot open some pages that used to be availble.

i also checked my pc with free online avast antivirus program, and it said no virus found on memory and files.

and there is always emerging the security alert box and recommend to re-register in some websites like www.regwinclean.com or refreshxp.com and etc ; everytimes this box come out, there is always different websites.

so i would like to know what is wrong with this problem and how to solve it out!

thanks for ur time.

What is wrong with my internet access and other window systems' speed got slow?antivirus protection

Sounds like spyware. Here are some solutions for ya...

Update and run your Anti-Virus program. Don't have one? You can run a free online scan from Trendmicro. When I have tested it it takes some time to run it but it may be time well spent if it can fix any problems.

Download and run http://housecall.trendmicro.com/

Download, update and run Spybot---http://www.safer-networking.org/ . Don't forget to use the Immunize feature.

Download, update and run Adaware---http://www.lavasoftusa.com/software/adaw...

Download SpywareBlaster---http://majorgeeks.com/download2859.html

SpywareBlaster doesn't scan and clean for spyware - it prevents it from ever being installed.