Help! Multiple Computers Freezing After Updates – Any Ideas?

I'm dealing with a frustrating issue that's been affecting multiple computers across a client's network. Initially, we noticed a few machines were becoming unresponsive, either at login or during normal use, and required a power cycle to get them working again. The situation escalated when the office manager found out that other PCs were also having similar problems, even if users hadn't reported them yet. We analyzed event logs and discovered that about 20 out of 40 PCs were rebooted without any clear cause. After extending our investigation to around 400 endpoints, we found over 200 computers power cycled in the last month and 117 just this past week. Most issues report unresponsiveness during morning logins. I'm thinking it's a larger issue at play, though I doubt all affected computers have the exact same problem. Notably, most of these machines, which vary widely in age, manufacturer, Windows version, and CPU, all show spikes in event ID 41, particularly after a Windows update on June 15th. Any insights or advice on what I should check next? I'm feeling a bit stuck!