It depends on your definition of "web freeze". If you are able to so much as contact another web site, the internet is working and the
web is not frozen. If you mean communications with a given site or an interruption of a given download I would term that a "session" freeze and there are any number of factors that could cause that. Initially I was going to attempt to list some things that might precipitate a "session" freeze but quickly realized they would not be comprehensible unless you know some basics about how
packet switching networks and how they work. That was going to take a LOT of explaining; more than I have time to write (not to mention probably more than you want to know).
If you are serious about digging into the technical details of how this all works
this Wikipedia article on ARPANET would be a reasonable place to start. (ARPANET is the first large scale packet switching network and established the fundamental technologies that later became the internet.) Once you have an idea of how a
packet switching network functions I think you will see at least some of the things that could cause a "session" freeze and if you are like me become amazed how robust this late 1960's very early 1970's technology has proven to be. I seriously doubt any of the original developers could have envisioned todays internet. When I worked for Microsoft in the mid 90s the corporate position was ethernet was all we needed to worry about because the internet was just a
geek fad. That was in spite of the fact that unofficially within the Microsoft engineering ranks we were rapidly becoming dependent on it.
