Outlook 2003 and accessing non http websites

Hi, I'm a new member so 'hello' to everyone.

I have a a couple of strange problems in my office and am running out of ideas.

1. A PC running XP and Outlook 2003 has recently stopped being able to send/receive email and been unable to view HTTPS or FTP sites. No settings have been changed. I have googled the problem and been advised to remove patch kb913807 (don't have it), turn off firewalls but with no luck - i am out of ideas

2. Have the same problem on a laptop, but this laptop works fine at other locations outside of the office.

Nothing has changed on our router and the other 5 PC's in the office work fine.

I beleive it has something to do with port permissions or opening them but i don't understand what could have caused the problem in the first place and why the laptop works at other locations.

Thanks on advance for any help