I have been using Internet Explorer 7 for about a year, since it was Beta1, updated to Beta 2, updated to Beta 3, and now have updated to Release Candidate 1 and haven't had any problems. It is a great Browser. I also have and sometimes use Firefox, but I prefer Internet Explorer 7. He should go to Microsoft or Windows Update site and get all the latest updates. If that doesn't work go to Add or Remove Programs and uninstall it. It will automatically revert back to Internet Explorer 6, then reinstall Internet Explorer 7, because it might have been a bad install. Below are the minimum requirements your computer needs to run Internet Explorer 7. Some components may require additional system resources not outlined below.
Internet Explorer 7 will run on Windows XP Service Pack 2 (SP2), Windows XP Professional x64 Edition, and Windows Server 2003 Service Pack 1 (SP1).
Minimum Requirements
Computer/Processor
Computer with a 233MHz processor or higher (Pentium processor recommended)
Operating System
Windows XP Service Pack 2 (SP2)
Windows XP Professional x64 Edition
Windows Server 2003 Service Pack 1 (SP1)
Memory For Internet Explorer 7:
Windows XP Service Pack 2 (SP2) - 87 MB
Windows XP Professional x64 Edition - 168 MB
Windows Server 2003 Service Pack 1 (SP1) - 87 MB
Windows Server 2003 Service Pack 1 ia64 - 218 MB
Drive
CD-ROM drive (if installation is done from a CD-ROM)
Display
Super VGA (800 x 600) or higher-resolution monitor with 256 colors
Peripherals
Modem or Internet connection; Microsoft Mouse, Microsoft IntelliMouse, or compatible pointing device
http://www.microsoft.com/windows/ie/ie7/about/sysreqs/default.mspx
Post any questions or problems you have to the microsoft public internetexplorer general newsgroup, either through a newsgroup reader or on the Microsoft Discussion Groups site.
http://www.microsoft.com/communities/newsgroups/list/en-us/default.aspx?dg=microsoft.public.internetexplorer.general&cat=en_us_28cca3eb-7037-4d4f-bde1-d8efee1f1420&lang=en&cr=us
http://www.microsoft.com/communities/newsgroups/list/en-us/default.aspx?dg=microsoft.public.internetexplorer.general&cat=en_us_28cca3eb-7037-4d4f-bde1-d8efee1f1420&lang=en&cr=us