League Crashing computer when opened

Since I updated to patch 6.5, my computer has crashed and needed to be rebooted every time I attempt to open League client. Everything else works fine, and I've installed antivirus and antimalware software, neither of which have detected viruses or malware. I have never had this problem before, and the article linked was of no help. The exact symptoms are as follows:

1. load patcher
2. hit play
3. Type in password and login
4. Login successful, opening client
5. Client loads, but appears black with outlines of announcements for a bit
6. announcements appear
7. everything but mouse freezes
8. mouse freezes
9. restart computer
10. everything is fine until League is opened

Any help is appreciated.