internet explorer cannot load a certain picture

Hi,
Internet explorer cannot load this picture:
https://www.parcelforce.net/images/validate.gif

i need to login to parcelforce and it is https zone as well, no problem, logs in, in next step, where i enter customer details, loads everything but stucks at loading this validate.gif picture, therefore i cannot carry on.

Firefox, however, loads with no problem, but since the system of parcelforce is not compatible with firefox, my only option is IE and it just does not work.

tried clearing all cache, deleting temporary files, upgrading/downgrading, adding the site in trusted sites etc etc.. nothing worked. completely uninstalled antivirus/firewall software, didnt help.

win xp.

please advise!