Strange ping issue

[klaxon4pk]

Hey guys,
I'm using windows 7 ultimate x64, I play counter-strike the ping is usually normal(20-25) until someone on the other computer on the network start downloading or just start watching videos, it keeps fluctuating between 25-400, it seems like a ISP problem but I don;t know what to do maybe you guys can help me.

Thanks, Klaxon

 

[klaxon4pk]

Sorry didn't knew I could edit the post..

 

[SlasherIT]

Downloading makes your ping higher as more bandwidth is used. Could you check pingtest.net and speedtest.net and post your results.