things do not always happen instantly on a computer as much as people would like it to it has to go through certain processes,
it seems from what you are saying ,
that you may have something nasty lurking inside your computer click on this link and do the on-line scan just to check,
http://www.bitdefender.com/scan8/ie.html
it will not do any harm just to check ,
after that if the scan finds you have something it may have destroyed some of your core files...
sort that out then upgrade to IE7 there are a lot of things that need to be changed to make it faster,
one of which is your tcp/ip protocol settings and if you do not know what you are doing you can realy stuff it up.
E mail me for more support to help you in this matter only....