Aside from a configuration issue there isn't very much that could cause this. As you're able to access your emails on other computers it doesn't appear to be an account issue.
Could you please confirm that your Windows XP machine is fully up-to-date? Do you have the same problem using the same machine but an alternate browser? Has anything on the computer changed recently, such as updates or installation of new programs?
Rachael J Help & Support Forum Team
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However, I think that Virgin web mail has changed the way attachments work fairly recently. There used to be a Choose your file box which came up after clicking "Attach a File", wheras now it immedaitely opens a Windows Explorer box. It seems strange that Chrome should have the problem as I was under the impression that Google developed the Virgin web mail system.