I've had this happen to me about 5 times now and it is supremely annoying. More so it makes buying items literally impossible.

I'm unable to reproduce the bug. Every time it happens, my mouse cursor glitches out and looks like a bunch of mouse arrows stacked on top of each other in a vertical line for a few seconds seconds before abruptly disappearing. I run the game with everything turned off and very low settings at 25 fps. I don't run any programs in the background when playing the game.

Hey Rickless, trying using Olaf and Reckless Swing a guy with the lightning shield buff, not sure if it will reproduce but once I did that (Swung at a shielded Singed I think) and my mouse went arrowed, I did it again and my mouse was fixed :/
(One time thing only though)

Or play hardcore, it always happens in a hardcore game

OK YOU GUYS GUESS WHAT-

I've been able to pinpoint that the cursor bug happens more frequently in the lane where the quarry and the drill meet (Quarry is the at the top right?), somewhere in that area, about a 2 second walk from the drill in that range your mouse has a higher chance of bugging out, happened to me twice in two games, was able to fix it by pointing at a dark area (In between a cliff at bottom lane, same side as the drill like the right side capture points but i pointed at the cliffs leading into the shield buffs)

1st game was using Ezreal, mouse bugged and came back soon after

2nd game as Vayne, took alot longer for mouse to go normal

you guys should all try setting priority to high on league of legends in your task manager and seeing if that resolves the issue

Oh I was also on the left side team

I've had the bug several times and it always happens after 5 minutes or so for me. After that i can only see a faint cursor is missing icon if i have a skillshot up. Once or twice it has corrected but only rarely and it is impossible to be a good team member after that as the store is close to impossible to use so you cant even continue your item build or fight effectively

i have had my cursor disappear in almost all of my dominion rounds as of late. i do not have a dxdiag for you but here are some things i've noticed.

1. typically disappears when cursor is near a tower or the edge of the screen.

2. also typically happens when i am using a lot of skills in a small amount or time or if im switching between certain skills. example: when i switched between Garen's Q and R and i selected an enemy the cursor disappeared after i selected the enemy.

another example was when i Q'd then quickly hit W and E. suddenly my cursor was gone and i had to play psychic mind games with my computer to keep from going to the edge of the screen.

3. i notice it also happens when i die with my cursor at the edge or on a tower.

If i hit g for a ping i see a stacked cursor thing appear (looks like a bunch of dashes stacked on top of each other) and i use that as my basis for selecting skill, clicking enemies, selecting items, etc.

sometimes it reappears in seconds, other times it takes minutes. Sometimes it doesn't appear until after the game is over.

Lane does not matter. It happens on bottom just as much as top whether on left or right.

EDIT: I am using a ATI mobility 5470. i also have LOL Replay in the background

I just had it happen on me. Played about 7-8 games without problems. Then I had a game where I had just opened up Adobe Reader 9.5.0 in the background and the problem occurred.

Running on latest AMD 12.1 Catalyst and problem's still here.