Did this particular workstation have a beta version of IE7 installed on it at one time?
I have seen circumstances where that later caused issues as well.
If so, before we go there, try resetting the IE default settings:
With Internet Explorer open, click on the Tools menu and select Internet Options. There, click on the Advanced tab and then the Restore Defaults button or 'Reset Internet Explorer Settings.' Lastly, click Apply and OK. Close & Reopen IE and test.
There are some extra steps needed to fully uninstall IE7 when a beta was present.
Remember, for Beta 1 you need to click on 'show updates' to see the IE 7 uninstall entry in add/remove programs.
For Beta 2 & later you can see the IE 7 uninstall entry as a standalone entry, no show updates required here.
If you don't see the uninstall entires even after following the above steps then do the following -
Go to Explorer/Tools/Folder Options/View - Enable the Show Hidden Files and Folders.
Go to Start Menu/Run paste the following code & press enter(check the exact path in your windows folder)
%windir%\$NtUninstallie7bet2p$\spuninst\spuninst.exe
OR
%windir%\$NtUninstallie7bet2$\spuninst\spuninst.exe
OR
%windir%\ie7beta3\spuninst\spuninst.exe
One other way to do it is to manually navigate to the path shown above and click on spuninst.exe.
Afterward, you can re-install IE7. Here's the link for convenience:
http://www.microsoft.com/windows/ie/downloads/default.mspx.
(If ya want my honest opinion, if the OS is XP, I'd tell ya to go back to IE6. But I know that's not a real fix.)
If the issue continues, your situation may be due to Spyware, Adware or Malware.
Try emptying your Internet Explorer temporary cache and then doing a scan and clean using either X-Cleaner Micro and/or Ad-Aware. Both are free.
X-Cleaner Micro:
http://tinyurl.com/357tuu
Ad-Aware:
http://tinyurl.com/lvov4
I hope this helps.
Please let me know what the ultimate resolution is.