Outlook Express 6 trashes my e-mails. HELP!!!!

I just got my new Dell Dimension 8200 with Windows XP last week and I’m having serious problems with Outlook Express 6.

PROBLEM:

Outlook Express 6 downloads my e-mails, but when I click on an e-mail title to read, it tells me that the e-mail “cannot be accessed” and suggests that the problem may be that I’m “out of disk space.” (With 80 GB free HD space, I don’t think that’s the problem.) If I then close Outlook Express and restart it, all of my e-mails are gone! gone from my online mail severs, gone from Outlook! I’ve lost a week’s worth of e-mails already due to this problem.

I’ve used Outlook Express for several years under Windows 98 and have never encountered this problem before.

ATTEMPTED SOLUTIONS:

I’ve already spoken to Dell technical support three times already, and no one I’ve spoken to yet has ever heard of this problem. One Dell technician talked me through reinstalling Windows XP from the Dell CD (using the “repair” option), but the problem remains.

I’ve also run through the Microsoft automated troubleshooting guides to no avail.

One odd thing about this problem is that sometimes Outlook Express 6 works fine, downloads my e-mails and allows me to read them. Then a day later I go to start Outlook, and my latest e-mails have disappeared! Ouch!