The number of outdated security certificates on the Bold is increasing over time. These outdated certificates prevent the browser (and apps) from accessing sites. To remedy this problem, you can export up-to-date certificates from the Firefox browser and import them to the Bold. Note, however, that importing new certificates seems to fix certificate-related issues when using the Opera Mini browser only. I'm not certain, but it may actually increase certificate problems with the BlackBerry browser.
1. On your computer, make a folder to which you'll export the certs.
2. Open Firefox and go to preferences (possibly options in the Windows version).
3. Select the Privacy and Security section on the left. Scroll down to the bottom to the certificate section.
4. Choose "view certificates."
5. Select a certificate and export. Choose the folder you made for the certificates as the destination. Repeat until you have all the certificates.
Life pro tip: you can select one certificate and then hold down the ctrl key and select more -- and then press export. By default they'll export as .pem certs, which is what you want.
6. Transfer the folder to your device's media card. I did this by USB. You could also shut down the device and put the card in your computer if you have a card reader.
7. On your 9900 go to "Options > Security > Advanced Security Settings > Certificates."
8. Press the BlackBerry Button. Select "Import Media Card Certs" from the menu and import the certificates.
9. Go through your certificate list and delete any expired ones you can so that they don't interfere with validation. I have two from Bell that cannot be deleted, but deleted the other expired and revoked certificates.
Note: if you have email set up, I think you can email yourself the certificates as attachments too, and import them through the email client, but I haven't tested that.