Whilst I'm not sure why it happens on some systems but not the majority, you need to update your OS as it is way out of date.
Currently we are on XP SP3 with other security updates since even SP3, these updates close vulnerabilities, which are being exploited and this could impact on your systems security.
Because you only have XP SP1 that will also limit what IE version you can use, so your IE version will also be out of date and have vulnerabilities that are also being exploited.