<engaging psychic powers.......>
I can say without a shadow of doubt........
"possibly"...
How the hell are we supposed to help? you given us nothing!!!...
Is it your ISP? (can we trust you know enough to say reliably "the signal is fine from my ISP")...could it be your wireless signal? modem? router? PC?
What you have given us is equivalent to someone saying "my car stops sometimes... what's wrong with it?"
But perhaps you know as much about cars as you do about PC's.. so that seams a perfectly legitimate question to you!!
Bah.. I give up