A few Vista users have had problems with McAfee Read through the threads below, there's a lot of info & fixes to try.

Vista + McAfee 2007 + LimeWire = dropping connection

“No Compromise” Vista-McAfee-Limewire Solution

Can't Connect With VISTA!


Some people have also had problems with Java 1.6.0_01. You could try this older version & see whether that makes a difference. Use the JRE offline installer & remove your current Java version before you install this one.
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11
Try the McAfee fixes first though, some people can run the latest Java update without a problem

If none of that helps & you're still having trouble...tell us the brand of your modem. There could also be a firewall associated with the apartment's internet, it's been known to happen.