Game totally freezes after playing 5 - 10 minutes, if reconnected then it freezes again after 2 minu

Sorry for my bad english, My pc is old but i have been playing LOL in this pc for the last 2 years without facing any issues at all. After updating the game to the latest patch, i played normal, ranked and ARAM matches, everything was fine. Last night i was playing a normal blind match and suddenly the game freezed. I could move the cursor but the map, players, minions everything got freezed. I had to ctrl+alt+del to end the process and found out that the client was working fine. I reconnected to the match and then it got hanged again after playing 2 - 3 minutes. I tried playing Call of duty, browsing internet, watching movies and there was no issue at all. Everything is working fine except this game. Since then, this thing is happening in every matches. This bug is not letting me to play this game anymore.

I restarted my pc, checked my RAM, HDD, CMOS, Graphics driver up to date, no windows update, tried compatibility mode xp sp3, running the client as admin, tried 'repair game files' option, tried changing resolution. Nothing worked and now im under 20 minutes leavebuster punishment. I have already lost hope to play this game again.

However, im using windows 7 32 bit version.