Unfortunately there's not much we can do beyond the guide you already looked at. Your best bet in these cases is to submit your BugSplat report with as much detail as possible and then follow up with a ticket to Riot Support.
You can see a bit more info on what exactly is going on here,
I got a BugSplat Error
1. BugSplat is Riot's critical and compatibility error reporting tool. It's used to identify game conflicts with your specific system.
2. Unfortunately, this means that these issues happen on a case-by-case basis and it's hard to offer a fix on the forums.
3. Some basic things to try include taking a look at this article in the KB, updating your DirectX, Video Card Drivers, Microsoft Dot NET Frameworks, Windows Updates, Reinstalling LoL
4. As mentioned, because these issues are system specific they are difficult to address on the forums. If you need additional help please make sure you submit your BugSplat report, follow up with a ticket to Riot Support and include your DxDiag report.