It might not be the browser at all. Now's the time to start updating drivers. I would start with the video card and DirectX 8.1. You should be able to get both by using Windows Update and by going to Dell's website.
If those don't work, try this in order only moving to the next step if one doesn't solve the problem (and remember to reboot after each one):
1) Uninstall any apps you've installed recently before the problem started occurring. Also uninstall any that you no longer use or ones that integrate with IE. Basically, clean up the system. I recommend reading the FAQ section here to find out about deleting Temp files (.TMP) and clearing cache in the browser (Tools->Internet Options->Delete Files). Of course, reboot to see any changes.
2) Use Windows Update to install any critical updates/patches.
3) Use scandisk first, then defrag the c: drive. Be sure to use CTRL-ALT-DEL and "end-task" on any process except Explorer before you run both. This will help ensure they don't get interrupted.
4) Use the msconfig utility: go to Start->Run and type msconfig and hit enter. Go to the Startup tab to view what loads with Windows. There might be a conflcit in here somewhere. Disable all the ones you recognize first and reboot. If that still doesn't help, continue to narrow it down or post back for additional help.
5) At this point, there's not much else it could be except possibly a hardware problem. I would continue updating any drivers you can think of and possibly "flash" the BIOS to the most current revision. Dell's website would have "how-to" outlined for you. Also, check the memory especially if you added some in the past couple months. It's quite possible that it has gone bad or is incompatible. Try running the system off it's original memory stick(s).
6) Last but certainly not least, backup important data (you can create another partition using a program like PartitionMagic and move data over, or use a burner if you have one), then format the drive. Proceed to reinstall Windows followed by the apps that you absolutely need. I recommend testing the system before you decide to reinstall everything.
Good Luck!! And remember, we're here if you get stuck...
~cdogg
"The secret to creativity is knowing how to hide your sources."
- A. Einstein