emails not being received


New Email
I am running a hotmail account on Mozilla Firefox, with a satellite interface using Astra 3. I know for certain that in recent weeks, at least 4 emails have been sent by others to me, which I have not received. I have no way of knowing how long this has been going on, or how many emails I have not received in total.
It might be a red herring, but about a month ago, I formatted the hard drive and re-installed Windows XP and all the upgrades, including service pack 3. This was to rid the hard drive of a trojan, which appears to be successful. All the missing emails that I know about for certain have occured since this re-installing, but that might just be a coincidence.
Is there anything I can do to cure this without changing my email service provider?