Running slow and IE shutting down are two seperate issues. IF IE is stable now run it for a while then turnthe add ins back on and see if the rpoblem recurs.
In the mean time you cna be addressing the slow down issue. All PCs slow down as time goes by. One reason is psychological. As you get used to a system your expectations inrease and the machine seems slower. Nothing you can do about this. The second reason is growing bloat on the machine. There are two solutions to the bloat issue:
1) Reformat and reinstall - this is the shotgun approach and the sign of a weak mind. (Many people at OSNN beleive in the periodic reinstall and I will likely get blasted for this comment.) If you go this route make sure you have the windows CD and ALL of the hardware drivers for your machine. You must be absolutely sue you back up any keys and any DRM liscences.
2) The kinder gentler approach is to go through your PC and remove any junk you have installed that you don't absolutely need. That includes going through add/remove programs, running something like ccleaner, defragging the HD, spyware scans, virus scans, geeting rid of utilities you hardly ever use, getting into your start up directory and removing all the annoying little things that clog up memory and that were automatically installed for you by other program. Before removing items google them and make sure they are junk ware...
3) Option 3 is to start upgrading. Faster HD, more RAM (up to 3 gig in XP), faster graphics card, faster CPU (bigger power supply to go with all that).
A hijackthis log posted here at OSNN will get you some advice on performance eating software that may not be worth hanging onto in your start up.
PS I'm running IE 6 and it seems to be getting more quirky lately. It hangs and I sometimes have to close IE and reopen it to get it working again. I chalk this up to another product improvement on MS crash Tuesday upgrades.