What browser version are you using? IE 8 or IE 9?
Are you using 32-bit or 64-bit browser?
When the browser opens look at Help | About Internet Explorer. If there's no mention of 64-bit, the 32-bit version is the default.
If it's a Win7 64-bit computer, you have two versions of Internet Explorer: IE 32-bit (the default) and IE 64-bit (cannot be the default). Shortcuts to both should be listed in your Start menu.
You should familiarize yourself with this FAQ: http://windows.microsoft.com/en-US/windows7/32-bit-and-64-bit-Windows-frequently-asked-questions
• Q&A: 64-Bit Internet Explorer
http://blogs.msdn.com/b/ieinternals/archive/2009/05/29/q-a-64-bit-internet-explorer.aspx
Windows Kernel event ID 41 error in Windows 7 or in Windows Server 2008 R2: “The system has rebooted without cleanly shutting down first”
http://support.microsoft.com/kb/2028504
The computer stops responding when an USB device resumes from the USB Selective Suspend state in Windows 7 or in Windows Server 2008 R2
http://support.microsoft.com/kb/974476