Bug splat,help!

Hello all.

I am unable to normally connect to loading screen after champ select because my game crashes and bug splat comes out.I reported it,even contacted support about this matter,and although they were helpful I still haven't find proper solution to deal with this issue.

Issue looks like this: After champ select I do go to the loading screen but I cannot connect to it.My mouse pointer is loading and after ~30 sec game crashes. FeelsBadMan

INFO: I can,however,play 1v1 games without any trouble.So,I can play but not 5v5?? Okay..

Another things is: I wanted to post a screenshot here a few days ago,so I came to loading screen and pressed Print Screen button (via lightshot),but nothing happened expect my mouse pointer changed to normal white arrow.Tried pressing it few times again and after ~30 sec,my screen minimized.Clicked on it and I WAS CONNECTED TO LOADING SCREEN. Woohoo! EDIT: However,I do get problems connecting every few games and bug splat comes even tho I use thing I said above^.

And it really worked - I come to loading screen and press print screen few times,window minimizes and I connect.However,when I don't press print screen,when I don't wait for 30 sec wanting to make screenshot,I get bug splat.What? Obviously I can connect and play but not on normal way? Why?

INFO: I have same PC and internet connection for 6 years (playing LoL with it for 4 ),BUT - I recently changed my operating system to Windows 7 and I have this problem since then? Before I had Windows XP (yea,yea...) but never had this problem but now after getting Windows 7,bug splat every game??

Please if you have an idea of why this is happening and/or how can I fix this help a summoner in trouble :D!