I was having a regular problem where After Effects would freeze up my whole computer when I was switching to File Explorer to find footage to import. The whole screen would freeze, the mouse wouldn't respond, CTRL+ALT+DELETE did nothing and after a few minutes the screen would go white and eventually come back. Even when it did, AE would remain unresponsive and need to be restarted. It turned out there was a really simple solution which can be fixed in the Preferences. In the import section, uncheck "Enable Hardware Accelerated Decoding". It's requires a restart but after that, the problem hasn't reoccurred for me!