internet speed problem

I tested my connection speed at speedtest.net did it 1 time and my connection was ok but my ping was very high about 600ms.I was surfing in the internet and suddenly i noticed that its taking too long to load a website.Then i test my connection at speedtest.net and it was 2mbps down than the first one and the ping was the same.I tested the speed at my other pc and the speed was ok like mine at start and the ping was about 10ms.I dont know what is the problem with my pc.This problem i think is started when i fully updated my pc.My second pc that is ok everytime and the ping is ok has no latest updates.Can anyone help me and if is possible to fix that problem?I have windows vista home premium

Wireless or cable? At speedtest.net, did you test for the same location? Ping speeds are hard to control for, but restarting your modem/router may help. Do you know that your PC is clean from viruses?

This may not be your problem, but sometimes ISPs will fluctuate their Internet speed based on demand.

Why is my Internet connection so slow? - Windows Vista Help

lemur said:

This may not be your problem, but sometimes ISPs will fluctuate their Internet speed based on demand.

Why is my Internet connection so slow? - Windows Vista Help

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Your computer would have consists of lots of datas that can make your computer very slow and your computer may be affected with virus or mallware, you can install antivirus and then you can check your internet speed here http://****************/internet-speed-test/ for better results