Issue may be a no. of things. The modem/router, if wireless will have an internal NAT firewall. Also, your boss might be blocking or the isp is blocking p2p. Try updating your Java to Java 1.5 (take the JRE). This might make a difference. If you've connected ok before but it's inconsistent, then Java might do the trick.

BTW if you're using McAffee firewall, then disable XP's firewall! This often makes the difference also. You shouldn't run 2 firewalls. Also make sure McAffee is configured for LW; Firewall configuration instructions (click on link)