USPS.com tracking not working

[win32ss]

Probably a bug:
USPS.com tracking (or "track your package") is not working, empty screen. With older Firefox or Opera is fine. WinXP SP3 32 bits.
I'm not developer, just like Supermium. Sorry if not true.

Originally posted by @Boytcho in #1038 (comment)

[win32ss]

This should have been posted in the "issues" section.

But yes I noticed this as well on tools.usps.com, but only on the first attempt. Further attempts are successful. Unfortunately I didn't get any console information on the failed attempt.