I figured out what the problem was!
So, for some reason, when I was in safemode, everything was working fine. Back in normal mode, I started disabling services - one by one... but the process was slow and painful. All of a sudden, I realized that everytime Access 'freezes', my network activity indicator goes up. So I ran a 'netstat' command from DOS and saw a long list of WAITING and TIMEOUT activities, and they all target one particular machine on my network. I didn't bother to try to understand why it chose that particular machine. Anyhow, I went and try to disable any "Microsoft Client/Server" services.
I disabled the "Workstation" service and it seemed to solve the problem. Windows describe this service as: "creates and maintains client network connections to remote servers." I have no idea why this particular process interferes with Access (particularly, in Design mode). Beats the living hell out of me.
I've looked around and there are people who have reported this particular problem, but did not find any solution to this. So there's my solution to my particular problem.
Edit: just want to add a note that stopping the "Workstation" service also stops the "Computer Browser" service, which means you can't access other computers on your network. Re-enable these services once you finish your work in Access. This is a pain, i know. I don't know why my computer has this particular problem. I'm thinking it must be some software I installed that changed the behavior of my network connection (I have VMWare installed, and I think it might be this guy).