Safari can't connect to https

Safari suddenly can't connect to any HTTPS site because it "can't establish a secure connection". This is on an administrator account, not a managed account. A different administrator account is able to use Safari with HTTPS, so must be something specific to my account, but I have no idea what. Google Chrome has no problems connecting to HTTPS sites. Things I have tried: * emptied Safari's cache * deleted Safari's preferences * reset Safari entirely * repaired Keychain (no errors found) * deleted Keychain (didn't help) * repaired permissions in Disk Utility * rebooted * hoped it would suddenly fix itself All of the google results I saw suggested either repairing the Keychain (which I tried and which did not help) or were only applicable if there were "Parental Controls" involved, which doesn't apply here. If I had to guess, I would think that wherever Safari is checking for "certificates" is somehow corrupted, but I could be wrong. I'm not even sure where to look for those - maybe ~/Library/?