Before I go into the question, Yes, we did check with our ISP and there are no problems there.
Now into the question:
Certain users (almost all) in our company have been experiencing sporatic internet access. Sometimes it is slow, sometimes it is fast, but more often than not, they can't access the internet at all.
I tried scanning for viruses, ad-ware, spyware, etc... but that all turned up negative. There is however an unusually high amount of network traffic, but it is not affecting intranet communications, just internet.
I followed the manual removal instructions for several viruses that might cause the users to not be able to access the internet, but that didn't help at all either.
I don't know what to do next.