Same issues. Here's my situation details.
Op System: Win XP Home Service Pack 3
Hardware: 4 gigs of ram, great nvidia card, Zero (0) Problems running game at best settings for over a year. Handles Skyrim at near max, etc. No stress to the system.
Software: Nvidia card recently updated to latest drivers 5 weeks ago.
Internet Provider: Clearwire Wireless high speed. Zero (0) problems streaming video of HD quality in 1080 resolution. Very reliable.
When disconnects began: As of two days ago. Never had disconnect problems EVER unless it was my IP crapping out due to a service interruption, which is again, an extremely rare thing. Check my account log for games played, hours played, and total disconnects. This all began 2 days ago.
Symptoms: Enter a match fine. Have a web radio station playing in the background, like I always do. Play with about a 62 - 98 total latency, time of day depending. It's very good. Game progresses, then the screen freezes. Web radio is still playing in the background. A small (and brand new!) gray box appears in center screen with a "reconnecting" orange bar.
The gray box with reconnecting bar will continue, in vain, to reconnect to the game. Again, web radio is playing for a looooong time while this is going on - my internet is NOT being interrupted for general use. It's not just the data buffer of the current song expiring.
Game will never reconnect. Must use Cntrl+Alt+Delete to pull up my task list and End League of legends to exit. Meanwhile, .PvP net will remain attempting to connect as a hidden process, which is stalled out in trying to reconnect. It is at this exact moment when I've Ended my League of Legends client from my Processes that my Web Radio goes out, because .PvP net process has jammed my IP data flow entirely.
Will not play game until this is solved, and I am very irate for the number of Drops that are now marked on my account because of the error involved that is on YOUR side, Riot.
Edit - side note: current game client was totally uninstalled and re installed as of 8 days ago or so. The install of the client is fresh and defragged.